Tag: spring

Bug o’the Week – Closed for June I – Scuds, encore by Kate Redmond

Bug o’the Week
by Kate Redmond

Closed for June I Scuds, encore

Salutations, BugFans,

The BugLady usually closes for the month of June so that she can hit the trails, find newly-minted insects (preferably ones that she hasn’t written about yet), and start building up a stash of pictures for future episodes – by spring, her picture files are dominated by unidentified insects.  Also, having hit 700 episodes at the end of March, the BugLady feels the need for a victory lap/vacation.  Never fear – there will be something buggy in your mailbox every Tuesday in June.

We’ve spent the last five weeks celebrating American Wetlands Month, but really, every day is Wetlands Day, so here’s an encore episode from 2011 that was in the queue when we ran out of Tuesdays in May.  New words; new pictures.

SCUDS

Sit down and put your feet up, it’s a long story.

OK, the BugLady could (and will) regale you with all sorts of arcane facts about scuds (aka amphipods or sideswimmers), but the main “take-home” here is that scuds are a hoot!  And they’re pretty cute, too.  What impresses people about scuds is their locomotion – they zip around in your collecting basin, pausing under the shelter of vegetation, and then they’re off again.  In The New Field Book of Freshwater Life, Elsie B. Klots says that they walk and crawl, “skittering’ on their sides by flexing and extending their entire body, and frequently rolling up on their sides or back.”  Anne Haven Morgan, in her Field Book of Ponds and Streams, adds that “Amphipods are accomplished water acrobats and can climb, jump, swim or glide with equal ease.”  

Their pedigree: Scuds aren’t insect “bugs”, but they are located under the giant umbrella of the phylum Arthropoda, along with insects, crayfish, scorpions, spiders, sowbugs, centipedes, fairy shrimp, and more.  Arthropods (“jointed legs”) are a mighty bunch that includes more than three-quarters of all animal species!  Within the arthropods, scuds are in the subphylum Crustacea, class Malacostraca, and the order Amphipoda.  That’s a bunch of big names for a small critter, and it doesn’t stop there – common names for this often indistinguishable bunch include freshwater shrimp, scud, sideswimmer, and gammarid (Amphipoda includes a large family, Gammaridae).  The taxonomy of these critters is, of course, under review.

Most Amphipods are Marine, but there are about 150 species of freshwater scuds in North America.  They are secretive bottom-dwellers, gracing cool, well-oxygenated springs and pools that have some calcium in the water for their shells (one source linked the size of scuds to the availability of oxygen in the water).  They prefer waters that are “fish-lite,” and they may grace these waters in huge numbers, up to 10,000 per square meter.  Look for scuds in tangled vegetation or under decaying leaves.  Through these thickets, they crawl and pull themselves along, using clawed legs and bodily contortions.  

Some species of amphipods are highly specialized, living in hot springs, caves, marine estuaries, or in deep, underground springs, and others are able to survive the drying of ephemeral ponds by burrowing into the mud.  The presence of some kinds of amphipods testifies to a waterway’s purity, but many species of scuds are tolerant of varying degrees of pollution.  They can’t live in poorly-oxygenated waters, and some species have fairly limited temperature “windows.”

The BugLady read of behemoth scuds that grow as large as an inch, but most are barely half of that.  Like a flea, a scud’s body is ultra-streamlined – arched and laterally flattened (if you look at them head-on, they’re pretty slim).  The front end (cephalothorax) consists of the head and the first segment of the thorax and is home to eyes, antennae, and mouth.  That’s followed by seven segments of thorax, with each segment bearing a pair of long climbing/walking legs (the first two pairs end in claws that are used in feeding and mating).  Gills are located at the base of the thoracic legs.  The last six segments are the abdomen, with six pairs of shorter appendages/legs that aid in locomotion and also push oxygenated water toward the gills (Amphipoda means “both kinds of foot”).  Scuds come in a variety of mostly neutral to pastel colors (influenced by their diet) and are often translucent.  Telling one genus from another may require a microscope.

So, how does a scud make sense of the world?  Scuds are light-averse, preferring starlight to sunlight.  Their two pairs of antennae are sensitive to both touch and smell.  While many amphipods see through well-developed, functioning, compound eyes, species restricted to caves and underground springs may be eyeless or have only vestigial eyes (but well-developed tactile hairs).  Normally-eyed species may evolve into blindness when restricted to permanently dark environs.

And where do little scuds come from?  Males and females swim piggy-back for days, preparatory to The Act.  If she needs to molt during that period, they separate briefly and then get back together after she has shed.  Like water sowbugs, female scuds have a structure called a marsupium on the underside of their thorax.  He passes sperm to her, and it mixes with the eggs (1 to 50 of them) in her marsupium.  She will carry the eggs around for one to three weeks until they hatch, and then she’ll carry the little tykes for an additional week.  If the dissolved oxygen in the water decreases, she may “ventilate” her marsupium by moving her first three pairs of abdominal legs to create a current.  The next time she molts, her fully-developed (but microscopic) young are released.  

The young scuds shed their exoskeleton eight or nine times on their way to adulthood (the exoskeleton splits across the back between two thoracic segments; the front half of the body is pulled out of the old exoskeleton first, and then the rear half), and adults continue to shed throughout their lives (which, if they’re lucky, may span more than two years).

The BugLady encountered a bit of amphipod ambiguity about whether a female breeds more than once.  Pennak, in his venerable Fresh-Water Invertebrates of the United States, states that most species of amphipods breed only once.  Other sources say that females can have several broods (up to 10) between April and October, but they must dance the dance each time.  According to Morgan, a female that produces 22 eggs every 11 days potentially has 24,221 offspring in a year (but egg mortality is high).

What do they eat?  Scuds are listed as detritivores, which means that they eat detritus – fragments of decaying organic stuff (including their own, shed skins) – from the water around them.  This “recycling” – breaking down organic materials into ever-smaller pieces for re-use by ever-smaller critters – is an important ecosystem service.  They also graze on the thin layer of algae, fungi and bacteria that covers submerged leaves, and although only a few species are predators, scuds may nibble on dying or freshly-dead aquatic critters.  They use those first two pairs of clawed feet to hold a morsel while they chew on it.  Scuds tend to live in waters too constricted and shallow for fish, but fish can be a major predator.  In the Western lakes where scuds were introduced as trout food, they make up almost a half of the trout’s diet.

If you Google “freshwater amphipods,” most of your hits will be photos and scientific articles, but if you Google “freshwater scuds,” you’ll find fishing sites and opportunities to buy scud-like lures. Several of the fishermen’s sites point out that scuds are related to shrimp and propose that although they are small, scuds might taste good in garlic sauce (what wouldn’t??). The presence of the usual compliment of parasites in scuds suggests culinary caution.

About the humble scud, the Pond Informer website says, “Apart from being nutrient recyclers, they collectively serve as a high-quality type of food for secondary consumers. They aren’t just consumed by fish; they are also a favorable prey type for larger crustaceans, wetland birds, amphibians, semi-aquatic reptiles, and riparian mammals. Gammarids are often considered ‘keystone’ species wherever they occur because their presence helps shape and establish working patterns for the existing ecosystem.” 

When she posted this episode in 2011, the BugLady said that it wasn’t known how scuds got from one pond to another.  She received an email from BugFan Don, who wrote, “Back in the good old days when I still went duck hunting, we would get ducks like bluebills and ring necks that had lots of scuds on their feet and leg feathers.  They would still be alive when we got the ducks home. To suggest that these diving ducks carry scuds from pond to lake is not unreasonable.

Duck hunters called them shrimp. I’ve heard stories about seeing retrieving dogs covered with the things.  These tend to be stories of the past, though.  No one seems to see scuds in such abundance any more.

The minnow sellers in western Minnesota have introduced fathead minnows into a lot of the big shallow lakes that were used by the divers [diving ducks] that fed on the scuds.  Bluebills leave Minnesota in worse shape than when they entered.  It takes a really severe winter to kill the fatheads so they tend to persist and they decimate the scud populations.  The divers responded by moving their migration and resting sites further west, into South Dakota.  The minnow merchants prospered, in spite of laws that prohibit moving live fish from pond to pond.” 

John Muir was right – everything IS connected!

Fun Fact about Scuds – according to J. Reese Voshell, Jr. in A Guide to Common Freshwater Invertebrates of North America, “scud” comes from a Norwegian word, skudda, which means “to push.”  The word was Anglicized as scud “and came to mean to move or run swiftly.”

Another Fun Fact about Scuds – an American scud that somehow made its way to Europe is out-competing the native scuds and is considered invasive.

Every day is a Wetlands Day.

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Wetland Homage V – Water Strider by Kate Redmond

Bug o’the Week
by Kate Redmond

Wetland Homage V Water Strider

Howdy, BugFans,

Rounding out American Wetlands Month, the BugLady would like to give a shout-out to our hard-working, home-grown Wisconsin Wetlands Association.  The WWA reminds us that 75% of Wisconsin wetlands are on private lands, and that effective wetland protection involves educating both landowners and policy-makers.  To learn about wetlands in Wisconsin, check the Wisconsin Wetlands Association website https://www.wisconsinwetlands.org/ (and they wouldn’t turn down a donation, either).

WATER STRIDER REVISITED   (2012)

Anyone who has watched Water striders in action has been wowed by the four-point shadow that marks their path over shallow waters.  Photographers chase them, often futilely – a literal flick of the wrist sends the wily Water strider out of focus at speeds of one meter per second.  The BugLady first wrote about Water striders in February of 2008 and decided to take a second look.  What she discovered changed the episode’s rating from “G” to “PG.”

Water striders are in the True Bug Order Hemiptera, and in the family Gerridae.  There’s also a family of half-pint Water striders called the Riffle bugs/Broad-shouldered Water striders, (Veliidae), and in some cases, it takes a microscopic internal examination to distinguish one family from the other.  Sources disagree about how many species we are graced with – estimates range from 45 to 85 species of Gerrids in North America and from 750 to 1,400 worldwide.  Most are found on quiet or slow-moving fresh waters, but about 10 percent live on salt water. 

They have lots of common/regional names – water spiders (they’re insects, but if you count more than six legs, take a nose-count, too; it might be two Water striders in tandem – more about that later), pond skaters, water scooters, magic bugs, water skeeters, and in some parts of the South, “Jesus Bugs” (because they walk on water).  Many species are long and thin; some have wings and others are wingless, and some species have both winged and wingless forms, depending on where they live.  Most measure half an inch or less, but there’s an eight-inch Vietnamese water strider that’s billed as the largest invertebrate working the water’s surface. 

Each pair of legs has a different task.  The short, hooked, front pair catches food; the second pair rows the Water strider from one place to another; and the third pair, the longest, may do a bit of rowing, but it usually steers.

How do they DO that?  The top layer of water molecules (the surface film) is “stickier” than those below because of its contact with the open air.  Water striders skate on the water’s surface film on tiny, non-wet-able hairs at the bottoms of their tarsi (the final leg segments – their feet).  According to J. Reese Voshell, Jr. in A Guide to Common Freshwater Invertebrates of North America, retractable claws are located above the bottoms of their feet, so the claws do not puncture the surface film as they skate.  Long, thin legs allow them to distribute their weight over a larger surface.

Their legs and bodies, too, are covered by hydrofuge hairpiles (water-repellant hairs), at a density of several thousand hairs per square millimeter!  Raindrops and splashes of water roll off without weighing the Water strider down, and if by chance they are submerged, air trapped in the hairs helps them bob to the surface and gives them something to breathe during the trip.  Water striders can hop up off of the water’s surface, and many species can fly.  When they are working the surface film, they breathe like terrestrial insects, through openings in the sides of the body. 

The folks at MIT have, of course, dissected Water strider propulsion.  The feet of Water striders create tiny dimples on the water where they sit.  When they locomote, their feet push down and back, forming a small indentation off of which they rebound, moving forward as if bouncing on a trampoline (for every action, there is an equal and opposite reaction – life is physics) (while they were at it, the MIT researchers built a Robostrider using an aluminum soft-drink can.  Of course.). 

What are they doing on the surface film, anyway?  A lot of eating.  They have, like other true bugs, piercing-sucking mouthparts.  Their prey are small terrestrial invertebrates that fall, or mistakenly fly, down onto the surface film and get stuck in it, sending out tiny ripples that mark their throes.  Water striders monitor the surface film with their front legs and skate toward the disturbance.  They also feed on tiny animals that float up from below, like emerging gnats and midges and mosquitoes.  Pierce, slurp, discard, repeat.   

Birds prey on Water striders, and so do some other aquatic Hemipterans, but because of a nasty secretion from their scent glands, only the hungriest fish will eat them.  If Water strider populations get dense, they may solve the problem with cannibalism.  They are sometimes infested by the red nymphs of Water mites.

Water striders practice Simple/Incomplete metamorphosis – they hatch (from eggs laid on plants and stones under the water or near its edge) looking like mini-adults.  They shed and grow over a period of about six weeks before reaching maturity, adding a few all-important adult appendages, living in the same habitat as the adults, and eating the same food.  The adults of the summer’s final brood overwinter at the bottom of the pond, in plant stems, or out of the water, sheltered along the shoreline in winter.  

Males and females defend their own territories during breeding season but abandon territories and congregate cooperatively at other times of the year, even sharing a “kill.” 

The BugLady discovered, upon revisiting the Water striders, that they have pretty gritty sex lives.  Here’s the “G-rated” version.  Water striders, especially males, do a lot of signaling in the form of ripples as they move about; they have ripple signals to communicate “repel” (when they want to be alone), “threat,” and courtship.  A male in courting mode may send out a repel signal to a passing Water strider, and if the signal is not returned, he sends out a courtship signal.  If she is receptive (female Water striders are the deciders), he may stick with her during the whole breeding period. 

And here’s the PG version: According to articles in Discover magazine in 2010 and 2012, reluctant brides of some common Water strider species may be blackmailed by males who skate up and grab hold.  If she resists his charms (by deploying a genital shield), he starts tapping rapidly on the water surface.  Researchers think this might have started off as a simple demonstration of his fitness, but the behavior evolved into something more sinister.  Another predator of animals caught in the surface film is the Backswimmer, who hunts from below, and ripples created by the male Water strider are known to attract Backswimmers to the scene.  Scientists postulate that the female, especially if she has encountered Backswimmers before, is aware of the danger (she is, after all, the one whose belly is closest to the Backswimmer – the male is shielded by her body), and she yields to the male in short order, whereupon he stops tapping.  They noted that males are aware of the Backswimmer’s presence and actually tap faster when Backswimmers are around. 

After the mating process, the male may stay on her back for up to two days, which hampers her hunting prowess. 

Evolution is at work again in the strategy developed by a small genus of Water striders.  When the male is a nymph, his antennae are only somewhat thickened, but in his final molt, the antennae develop dramatic hooks and spines that match the shape of the female’s head and eyes and allow him to grasp her more firmly (even so, seven out of eight females manage to elude him). 

Magic bug indeed!

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Wetland Homage IV – Water Scorpions by Kate Redmond

Bug o’the Weeku
by Kate Redmond

Wetland Homage IV Water Scorpions

 Howdy, BugFans,

If wetlands are the transitional spongy/submerged/semi-submerged/sometimes-submerged areas between high ground and deep water, what might some wetlands look like?  Swamps are wet woodlands, while marshes are wet areas with standing water whose vegetation is mostly non-woody.  Peatlands like bogs, which have no sources of water other than precipitation and run-off, so water stalls there and becomes acidic; and fens, which are fed by springs and are often alkaline.  And then there are sedge or wet meadows, scrub/shrub thickets, and more (for more info, see https://dnr.wisconsin.gov/topic/Wetlands/types.html) and https://www.wisconsinwetlands.org/learn/about-wetlands/wetland-types/.

WATER SCORPION (2008)

The long (about 2” not including the “tail”), lean, well-camouflaged Brown Water scorpion (Ranatra fusca) is in the order Hemiptera, and thus, it can legally be called a “bug.”  It’s in the family Nepidae, which includes about 13 species in North America and 270 worldwide, including some broader-bodied species like https://bugguide.net/node/view/2205541/bgpage and https://bugguide.net/node/view/818188/bgpage that resemble the Water scorpion’s distant cousin, the Giant water bug https://bugguide.net/node/view/1657638/bgimage. 

Water scorpions have simple/incomplete metamorphosis, looking when they hatch pretty much like they will as adults, adding a few parts (the wings and the “naughty-bits”) as they molt (five times) and mature.  As is typical with insects that practice simple metamorphosis, both the adult and the immature water scorpions live in the same habitats – muddy-bottomed ponds and very slow streams with submerged vegetation – and both dine from the same menu.  What’s sauce for the goose is sauce for the gander.

They hang out, usually head-down https://bugguide.net/node/view/1682158/bgimage, on aquatic vegetation and in the detritus just off-shore, gripping with their second and third pairs of feet, legs bent.  Their passage through the water is sloth-like, and swimming, also using their second and third pairs of legs, is not their forte.  In fact, in A Guide to Common Freshwater Invertebrates of North America, author J. Reese Voshell, Jr. says that water scorpions are so sedentary that not only do algae and micro-invertebrates form colonies on them, but other aquatic insects may deposit eggs on them!  This immobility is part of their “stealth” hunting tactic.  

They’re equipped to fly https://bugguide.net/node/view/126649/bgimage, and fly they do, but not often, and almost always at night (say most – but not all – sources), and they must emerge and spread and dry their wings before take-off.  They are known to bask in the sun.

Despite their resemblance to the terrestrial, vegetarian walking sticks https://bugguide.net/node/view/1874213/bgpage, water scorpion are carnivorous, ambushing aquatic invertebrates like daphnia, seed shrimp (ostracods), backswimmers, water boatmen (a favorite), and even tiny fish fry and tadpoles.  They spot their prey with protruding compound eyes https://bugguide.net/node/view/1679712/bgimage, “lunge” at it by straightening their legs suddenly (without letting go), nab it with mantis-like front legs, stab it with a short beak (which is capable of piercing human skin, so handle with care), and inject it with tranquilizers and tenderizers.

Two long filaments on their south end are not stingers, but they explain the “scorpion” part of the name.  These lock together to form a breathing tube, the tip of which the bugs position just at the air-water interface.  Oxygen seeps down the tube and is stored as a bubble under the fore wings, against the abdomen.  They can use that bubble of air when they want to go deeper than their “snorkels” will reach (the structure of the filaments doesn’t allow water to enter), and in well-oxygenated water, oxygen suspended in the water can diffuse into the bubble, giving the insect extra breathing time. 

According to a website called the Pond Informer, “The mating process for water scorpions typically occurs in the months of April and May. To attract a female mate, a male will perform stridulation. He will create a chirping sound that is produced when he rubs his legs against his body, similar to crickets rubbing their wings together. Once he has attracted a mate, the male water scorpion will lay diagonally across and on top of a female, and he will grab onto her thorax using his front legs. Shortly after mating has occurred, the female will deposit her eggs – she usually does this around dusk.” 

Her eggs, which are laid at or above the water’s surface in plant stems, rotting wood, or in damp spots like algae and moss near the water’s edge, have respiratory filaments that protrude from the eggs and allow them to take in oxygen https://bugguide.net/node/view/1861200/bgimage, and some sources say that the eggs can also glean oxygen from the plant stems they are inserted into.  She can lay about 30 eggs in one evening.  Newly-hatched nymphs make a dash for the water’s surface (there’s no room for breathing tubes in the egg https://bugguide.net/node/view/570259/bgimage).  

Water scorpions overwinter as adults, under the ice, equipped with a chemical defense against freezing.

Fun Fact about Water scorpions – an alarmed individual may squeak, and then it may play dead, and it may squeak if it’s scooped out of the water.  

Another Fun Fact about Water scorpions – they can sense the depth of the water they’re in by the water pressure.

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Wetland Homage III – Water Fleas by Kate Redmond

Bug o’the Week
by Kate Redmond

Wetland Homage III Water Fleas

Howdy, BugFans,

We’re celebrating American Wetlands Month with up close and personal views into the lives of some of its citizens, as seen in some slightly refurbished, vintage BOTWs.

Wisconsin has about five million acres of wetlands these days, down from an estimated 10 million acres 150 years ago.  Early explorers referred to this territory as the Great Swamp, but today, only about 15% of the state is covered by wetlands.  Wetlands were considered waste areas that needed to be turned into something “more productive,” and they were drained and filled and altered, and many were used for dumps.

DAPHNIA(2012)

Back into the water we go and into the realm of another NETI – not the pot, the “Not-Exactly-True-Insects.”  Daphnia are at the lower limit of what the BugLady can accomplish with her 50mm macro lens (though she does have a recognizable shot of a Cyclops……), and Daphnia, aka water fleas, are yet another example of great stories coming in small packages. 

How small?  Pretty much at the edge of what the naked eye can easily detect/identify.  One source describes them as the size of the “equals” sign on the keyboard.  They’re listed as less than 5mm. 

The short version – daphnia are oval-ish, shape-shifting, widely-distributed, exhaustively-studied (right down to the pH of their teeny-tiny digestive tracts), unbelievably fecund, highly variable, planktonic, freshwater crustaceans.  That sentence bears a little “unpacking.” 

Who are they, scientifically speaking?  Daphnia are in the Phylum Arthropoda, subphylum Crustacea (like the water sow bug of recent BOTW fame), class Branchiopoda (with fairy shrimp and a few others), order Cladocera, and the family Daphniidae.  For our purposes one of the more common daphnia, Daphnia pulex, will serve as Everydaphnia.  According to Ann Haven Morgan, in her lovely Field Book of Ponds and Streams, “In 1669 the Dutch naturalist Jan Swammerdam described the common water flea as Pulex aquaticus arborescens – ‘the water flea with the branching arms’ – and ‘water flea’ it has remained ever since.”  It was officially described and welcomed into the Linnaean system in 1785.

You can see what?  A translucent carapace/shell of its own creation wraps around the daphnia’s thorax and abdomen.  The carapace looks like a tiny bivalve/clam-type shell, but it is actually a single, “folded” piece that doesn’t quite meet on the ventral (belly) side, forming two “valves” but with no hinge.  Neither the segments nor the first pair of antennae can be seen easily, and the legs are found in the gap between the edges.    

Based on an exhaustive study of daphnia anatomy, the BugLady figures that the dark ovals that can be seen on the dorsal side in some of her Daphnia pictures are young in the brood chamber.  The front blob on the adult’s head is the eye, and the second blob in the head seems to be part of the intestinal tract.  Unlike (almost all) insects, which do not molt after achieving maturity, daphnia molt about 25 times in their lives, and when they are in reproductive mode, they release a brood each time they molt.

How do they navigate their world?  Daphnia are found in all sorts of aquatic habitats, including ephemeral ponds but not including fast-moving or polluted waters.  Its large, compound eye rotates constantly, sensing changes in light intensity – daphnia don’t like light much, and many species move up and down in the water column from a pond’s surface to its floor several times during a 24 hour period.  The mouth, the small, first antennae, and the setae (hairs) on the ventral edge of the shell pick up “smells.”  These hairs on the ventral edge of the shell and the sensory hairs on the antennae are their touch “organs.”  They breathe through their body surface.  “Rowing” movements of the larger pair of antennae also provide the jerking locomotion that earned them the water flea moniker. 

Most individuals live only a short time, but some may live about a year, eating organic detritus, bacteria, algae, and some micro-zooplankton and dodging their many predators.  A current set up by their legs delivers food into the mouth.

Sex – or not: As soon as the water starts to warm, offspring are produced solo, by Mom (a talent called parthenogenesis).  She’s pretty good at it, too, popping out as many as 40 at a time, all female.  According to Morgan, “one Daphnia pulex produces a brood of eggs every two or three days [other sources said 10 days] and with its descendants it is said to produce 13,000,000,000 in 60 days.”  It only takes the young a few molts to achieve reproductive adulthood, and when they do, they already have eggs in their brood chamber.  Daphnia eggs hatch in the brood chamber, and the young stay there for a few days; they are released when Mom molts, at which time she reloads the brood chamber. 

While she is cranking out more and more offspring, the water temperature is changing (warming in summer or cooling in fall), the water is getting more crowded, food is declining, and the concentration of waste products is rising.  These stressors cause her to produce some male offspring (up to 50%), and orgies ensue.  The eggs produced by these sexual unions (which introduce some genetic variation) are called winter eggs.  Extra layers are added to the walls of the brood chamber for the winter eggs.  The whole “egg container” is called an ephippium, and the egg-filled ephippium is released as a unit that can survive winter cold and drought.  If the drought is temporary and the pool refills in fall, the eggs in the ephippium hatch (most of them are female) and the cycle is repeated. 

Shape-shifting?  The warming waters of summer may (or may not) cause individuals to change the shape of their head/helmet from rounded through pointy to absurdly pointy.  Predatory pressures may result in smaller, more transparent individuals that may grow neck spines (yes, the BugLady is a sucker for cool graphics – https://www.nd.edu/stories/little-giants/).  Here’s more https://northernwoodlands.org/outside_story/article/daphnias-changing-shape-stirs-a-debate.

Who cares??   Well, fish care – a lot.  Daphnia are bread and rice to many young fish, comprising up to 90% of their early diet!  Carnivorous bladderwort plants care, too; Morgan says that one bladder can hold up to three daphnia.  Aquatic insects also appreciate them, and wading birds.  Aquarists (not Aquarius’s) care – daphnia provide food for aquarium animals.

Scientists care.  The translucency of their carapace allows scientists to watch a daphnia’s innards at work.  Daphnia are almost universally available, are easy to rear in the lab/school, and look cute under (and can survive under) the cover slip of a slide.  You can subject them to alcohol, nicotine, prescription drugs, etc. and watch their reactions, study immunity, disease, cellular function, and more. 

Scientists are so enthralled with daphnia that they have worked out the genomic sequence (which wades deeper into scientific waters than the BugLady is comfortable going).  Suffice it to say that humans have 20,000 to 25,000 genes and daphnia have 31,907, more than one-third of which are unique to daphnia, and many of which are duplicates!  One of the legacies of the late, great entomologist Dr. Tom Eisner is the mantra that knowing the natural history of an organism can help us hypothesize what is/isn’t/should be happening internally.  Daphnia are short-lived critters that survive in constantly-changing conditions, and scientists think that the environment may help determine which of the duplicate genes will be expressed. 

The rest of us care, too.  In his Freshwater Invertebrates of the United States, Pennak says that “the water fleas have been favorite objects of observation by both amateur and professional biologists ever since the invention of the microscope.”  The BugLady was charmed to discover that there are daphnia tee-shirts.

And we can barely see them! 

Life is Physics. The various creatures of the surface film have developed different ways to navigate the meniscus—Water treaders actually “run” at the meniscus slope and then use their front legs to pull themselves “uphill.” The BugLady recommends this beautifully-photographed article about bugs and https://thales.mit.edu/bush/index.php/2005/04/14/wetting-climbers/ (you don’t have to do the math–the folks at MIT already did it for you).

Bugs in culture: “I was stunned by the perfection of the insects.”—Pablo Neruda

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Wetland Homage II – Water Treader by Kate Redmond

Bug o’the Week
by Kate Redmond

Wetland Homage II Water Treader

Greetings, BugFans,

The celebration of American Wetlands Month continues.

We’ve all seen the list of wetland benefits – wetlands recharge groundwater, protect us from floods by trapping water and releasing it slowly, improve water quality by absorbing pollutants and sediments (they’ve been called “the kidneys of a watershed”), protect shorelines from erosion, and provide recreation and beauty.  And they’re amazingly productive, biologically – they provide homes and habitats for many plants and animals (for 75% of Wisconsin wildlife species, says the Wisconsin Wetlands Association), and according to the Defenders of Wildlife organization, “More than one-third of our country’s threatened and endangered species live exclusively in wetlands, and almost half of these imperiled species use wetlands at some point in their lives.”  They are considered as productive as coral reefs and rainforests, and they feed us and multitudes of other animal species (“biological supermarkets,” said one report).

Without further ado — WATER TREADERS (2014)

As the BugLady was leaning over a pier photographing aquatic stuff last summer, she saw a mugging.  Turns out that she misidentified both the muggers and the mug-ee (and, probably, the motivation).  She thought that she was seeing a pair of young water strider thugs attacking a guiltless Mirid plant bug.  The two “water striders” rushed across a water lily leaf and grabbed the larger “plant bug” and scuffled with it, actually rolling it onto its back.  As the BugLady snapped pictures, the “plant bug” managed to get away and exited across the leaf to the left, while the delinquents ran away to the right. 

Fast forward eight months, when the BugLady was researching the Water lily planthopper (of recent BOTW fame).  One reference noted that “Water lily planthoppers are preyed on by Water treaders.”  Water treaders?  When the BugLady looked them up, she recognized them as the young hoodlum bugs (Water treaders are not to be confused with the larger, more delicate Marsh treaders—a whole different animal).  The third bug was also a Water treader.

And, when the BugLady looked at the pictures again, very carefully, she realized that what she initially interpreted as a mugging might instead have been two Water treaders sharing an intimate moment and being relentlessly interrupted by a third.

Mulsant’s Water treader (Mesovelia mulsanti), named after a 19th century French entomologist-ornithologist, is fairly common in eastern North America and points south but is easily overlooked and has a history of being ID’d as the nymph of something else (which, of course, the BugLady did, too).  In the introduction to his 1917 publication “The Life-History of Mesovelia mulsanti,” H. B. Hungerford says that it “seems worthwhile to present some notes concerning the biology of Mesovelia mulsanti whose habits and life-history are certainly among the most interesting of all the bugs that walk upon the surface of the inland waters.” He proceeds, cheerfully, to do just that. 

“It is at home in the haunts of the marsh-treader on the floating vegetation growing in the shallow waters of the pools, where the clumps of sedge spread their slender stems upon the water from the bordering bank, where young cattails spring up and green algae carpet the surface of the waters.” (more Hungerford).

Mesovelia are about 5 millimeters small (1/4” max), with long antennae, long legs, and a long face.  Nymphs and most adults are silvery-green.  Like the water lily planthoppers that they dine on, adult Mesovelia come in uncommon winged forms – dark, with a white chevron on their backs (https://bugguide.net/node/view/1683522/bgpage) – or more-common wingless forms (there’s an “in-between” morph, too).  Their long legs allow them to scoot along pretty fast on the water’s surface and on vegetation, and to take little hops.

They have a simple/incomplete metamorphosis—a newly-hatched individual (a nymph) resembles an adult.  Food-wise, what’s good for the adult is fine for the nymph, and they sport sharp, piercing mouthparts.  Contemporary authors describe a fairly languid/passive hunting style, saying that WTs feed by scavenging dead or injured insects or insects that are stuck on the surface film (and that they may practice cannibalism).  Earlier researchers like Hungerford tell us that “Water Treaders eat insects and other small invertebrates; their hunting method is to run along the surface of algae and duckweed, and even along the surface of the water, until they have run down their prey.”

It’s not surprising to see them on a water lily leaf with aphids, and in the picture of the damselflies, the BugLady presumes that the female Skimming Bluet damselfly (the caboose of the tandem pair) was nipped in half by a hungry bird, and when the male landed on the water lily, the Water treader was attracted by the female’s hemolymph (bug blood). 

They also reach down through the surface of floating mats of algae and other plants and snag tiny crustaceans and aquatic insects that feed and shelter there.  When they catch something, they insert their “beak,” inject saliva/enzymes, and suck out their prey’s innards.

Hungerford again: “They are cautious creatures but do, on occasion, fall upon fairly lively prey. The tiny nymphs feed upon more gentle organisms in the water as there are few upon the surface that they are able to overcome. When offered springtails as suggested by Butler, disaster often followed…the hungry little creatures would attack them, only to be turned topsy-turvy upon the water even by comparatively small springtails.”

Mesovelia are eaten by fish and dragonflies, and nymphal water mites may parasitize them.

Ms. Mesovelia uses a specially designed ovipositor to pierce the stems of aquatic plants and ream out a hole.  She may lay as many as 100 eggs, each requiring a separate incision (“As frequently as not the male accompanies the female during the process. Having mounted her in mating he merely moves forward and remains perched upon her back as she busies herself with egg laying, mating being attempted and often consummated between her labors.” Hungerford).

The plants that she inserts her eggs into sink to the pond floor in winter and according to some accounts, the eggs hatch in spring.  There are probably several generations through the summer, but sources disagree about whether the final bugs of the year overwinter as eggs or as adults, hidden in the shoreline debris, bolstered by an internal antifreeze that keeps lethal ice crystals from forming in their cells.

Water treader vocabulary word—one of the two species of North American Mesovelia that have found their way to Hawaii is troglophilic.

Where do Mesovelia fit into the great scheme of things?  Within the order Hemiptera, in the infraorder Gerromorpha (infraorder is one of those potential notches between order and family that’s used as needed).  The Gerromorpha include water measurers, water striders, smaller/riffle/broad-shouldered water striders, and a few others.  As a group, they are sometimes called “semiaquatic bugs” or “shore-inhabiting bugs,” and one author calls them all “pond skaters.”  They are often seen locomoting across the surface of the water (including salt water— bugguide.net calls them the only true marine insects).  Water treaders are in the family Mesoveliidae.

How do they do it?  A “hydrophobic” (waterproof) cuticle and hairs are standard equipment on the Gerromorpha, and their long, water repellant legs allow the pond skaters, whose weight is therefore spread out, to push down on the water’s surface without punching through.  Check the indentations on the surface made by a water strider https://bugguide.net/node/view/1751576/bgimage (curiously, the claws of a water strider are located up on its legs in order to avoid slicing the surface film, but a Water treader’s claws are in the normal spot at the ends of its tarsi). 

Another Water treader vocabulary word is meniscus (the curve of the upper surface of a liquid, caused by surface tension).  There’s hardly a concept more important to aquatic invertebrates than surface tension.  Because it is in contact with the air, that top layer of water molecules is “stickier” than those under it, and a certain force is needed to break through it, whether from above or below.  The “meniscus effect” results in tiny, slippery hills where the water’s surface curves up to meet the “edge” of the shoreline, and of plant stems, leaves, floating debris, etc.

Life is Physics. The various creatures of the surface film have developed different ways to navigate the meniscus—Water treaders actually “run” at the meniscus slope and then use their front legs to pull themselves “uphill.” The BugLady recommends this beautifully-photographed article about bugs and https://thales.mit.edu/bush/index.php/2005/04/14/wetting-climbers/ (you don’t have to do the math–the folks at MIT already did it for you).

Bugs in culture: “I was stunned by the perfection of the insects.”—Pablo Neruda

Kate Redmond, The BugLady

(Sharp-eyed BugFans who are wondering about the tiny, elongated, shapes in one of the pictures – good spotting – those are Cyclops https://uwm.edu/field-station/cyclops/)  

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Wetland Homage I – Water Sow Bug by Kate Redmond

Bug o’the Week
by Kate Redmond

Wetland Homage I Water Sow Bug

Howdy, BugFans,

May is American Wetlands Month.  So, all month, BOTW will celebrate by posting slightly-massaged (a few new words and pictures), encore episodes about a selection of awesome critters the BugLady has encountered in area wetlands, plus some wetland information.

To start with – what exactly is a wetland?  There are some pretty technical definitions out there that include wetland soil types and lengths of time that soils are submerged, but the US Geological Survey’s definition is more intuitive.  Wetlands are transitional zones between well-drained upland areas and deep water systems.  The water table in wetlands may be at or just below the surface of the land, or the soil may be covered by shallow water.  Some wetlands are permanently wet; some are periodically dry; some are wet at high tide.  The BugLady is reminded of a video she once saw of Canadian Naturalist John Acorn, wearing boots and standing in a squishy area, saying “Wet!  Land!  Wet!  Land!” as he lifted and put down one foot and then the other.

WATER SOW BUG

This story about Water Sow bugs was first posted in 2009.

Another foray into the world of the “almost-insects.” Like insects, Water Sow Bugs are in the Phylum Arthropoda (“jointed appendages”), and like their terrestrial cousins the sow/pill/potato bugs of previous BOTW fame, they are in the very diverse subphylum Crustacea (with lobsters and crabs and barnacles and more) and in the mostly-aquatic Order Isopoda (equal foot), a reference to their abdominal appendages.  They’re in the family Asellidae, the Common Waterslaters.  The BugLady couldn’t find any explanation for “waterslater,” and when she looked up “slaters,” it was defined either as 1) “someone who lays slate” or 2) as a water sow bug.  Maybe a reference to the overlapping segments of the exoskeleton?  The water sow bugs she photographed might be in the genus Caecidota.  

About the common name—they were named sow bugs because someone thought that the way the female cares for her young was reminiscent of sows caring for piglets.  Other names for these critters are water louse, aquatic sowbug, water hoglouse, and cress bug.

They are flattened for crawling under stuff, drab in color, and about ½” long.  They have three body segments—a cephalothorax (combined head and first segment of the thorax), a thorax (the next 7 segments) and an abdomen (everything south of that).  Jointed appendages?  They’ve got plenty.  Water sow bugs have 7 pairs of legs, one per segment of the thorax.  The first pair is adapted for holding; the rest of these boots are made for walking.  To that, add 6 pairs of short appendages on the underside of the abdomen, the final pair of which looks like two tails.  They breathe using gills located on the underside of the abdomen, and there are two pairs of antennae – one long and one short. 

Look for Water sow bugs in shallow water under dead leaves and debris – the more hiding places there are, the more Water sow bugs there will be.  One source calls them “secretive.”  They are designed to survive in low-oxygen and they prefer the lighting to be low, too.  Diet-wise, they are omnivore/scavenger/shredders that eat little pieces of detritus from the pond floor, bits of dead or injured animals, and live and decaying plants.  In turn, fish and many other aquatic animals eat them.

On the underside of each of the segments of the thorax, at the base of each leg, is a short, inward projection; these combine to form a shallow chamber below the thorax.  Female Water sow bugs use this thoracic chamber as a brood chamber or marsupium https://bugguide.net/node/view/1799296.  She carries her eggs there, and later, for a little over a month until they can fend for themselves, her young.  During that time, she fans the “plates” that form the marsupium so that the eggs/young are properly oxygenated.  That maternal solicitation is negated by the fact that she will sometimes eat her own offspring, and that the siblings may cannibalize each other.  

Wood frogs owe a lot to Water sow bugs.  Water sow bugs help to turn big pieces of dead plants and animals into little ones in ephemeral ponds. In the process, dead material is removed from the pond, and smaller chunks of material can be colonized by fungi and algae more easily.  These nutritionally-enhanced morsels of food are eaten by wood frog tadpoles and other herbivores. 

Fun Fact about Water sow bugs: though they live underwater, they are poor swimmers, getting from Point A to Point B by crawling.  Slowly. 

Another Fun Fact about Water sow bugs:  Old Wives say that if you have an upset stomach, you should eat a sowbug.  Turns out that (like Tums) their exoskeletons are largely calcium carbonate.

And if the worst that can be said of any of us, after we pass, is that we maybe cared a little too much for watercress, then we will have lived pretty blameless lives, indeed.

Kate Redmond, The BugLady

(Sharp-eyed BugFans who are wondering about the tiny, elongated, shapes in one of the pictures – good spotting – those are Cyclops https://uwm.edu/field-station/cyclops/)  

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Nature Tots and Little Explorers End of Season Celebration

June 8 @ 11:00 am – 1:00 pm

Nature Tots and Little Explorers End of Season Celebration- CANCELED

We’ve had so much fun together over the year so let’s celebrate with an end of the season picnic! Please bring your own lunch/beverages and come ready to play with your friends! Riveredge will provide some self-guided and educator-led activities for you to enjoy at your own pace.

For children ages 1-5 and their families

Members: $3 | Non-members: $6

Y’all are busy bees! Event cancelled due to low registration. Check out our summer tots classes, Green Thumb Gardeners, one Saturday a month!

 

Members:

Be sure to sign in to your account in the upper right corner to activate your membership benefits. Membership discounts on programs will be applied to your cart at checkout. If you haven’t created an account with our new system, be sure to create one using the email address associated with your membership.

If you need to check your membership status or you aren’t sure what email address we have on file, please reach out to our Membership Manager, Renee Buchholz at rbuchholz@riveredge.us.

To become a member, click here

How to Register as a Member
Cancellation Policies

June 8 @ 11:00 am – 1:00 pm

Riveredge Nature Center

4458 County Hwy Y (Hawthorne Dr)
Saukville, WI United States + Google Map
(262) 375-2715

Growing Green: Companion Planting and Container Gardening

June 14 @ 5:00 pm – 6:00 pm

Growing Green: Companion Planting and Container Gardening

“I get by with a little help from my friends.” The Beatles say… your garden agrees! Learn all about companion planting from lifelong organic gardener, Mary Ann Ihm, as well as tips and tricks for successful container gardening.

Meet at the Riveredge main Visitor Center.

Ages 14+

Members: $5 | Non-members: $10

Pre-registration required by June 13 at 11:59 pm

Register Here


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Members:

Be sure to sign in to your account in the upper right corner to activate your membership benefits. Membership discounts on programs will be applied to your cart at checkout. If you haven’t created an account with our new system, be sure to create one using the email address associated with your membership.

If you need to check your membership status or you aren’t sure what email address we have on file, please reach out to our Membership Manager, Renee Buchholz at rbuchholz@riveredge.us.

To become a member, click here

How to Register as a Member
Cancellation Policies

June 14 @ 5:00 pm – 6:00 pm

Riveredge Nature Center

4458 County Hwy Y (Hawthorne Dr)
Saukville, WI United States + Google Map
(262) 375-2715

Bug o’the Week – Variegated Meadowhawk Redux by Kate Redmond

Bug o’the Week
by Kate Redmond

Variegated Meadowhawk Redux

Salutations, BugFans,

Variegated Meadowhawks started appearing in the state from the south and southwest in mid-April this year.  Their appearances were brief – they have places to go – but they leave eggs behind in our ponds.  Their offspring will emerge in late summer to decorate our landscapes briefly before they leave, too.

BugFan Freda contributed in-flight shots of Variegated Meadowhawks that she took recently at a local pond.  Note that one of Freda’s pictures shows a pair flying in tandem, with a third dragonfly, another male, that’s investigating/trying to break up the pair.  That’s the reason why, in many (but not all) species of dragonfly, the male continues to clasp the female as she oviposits (contact guarding).

The BugLady massaged this episode from 2012 – some new words and new pictures.  As you may recall, spring arrived in February that year, though we bounced back to normal in May, just in time to freeze the apple and cherry blossoms.  It was a long, hot, dry summer – water levels dropped, and plants bloomed early and only briefly before getting fried – and butterfly and dragonfly populations took a hit.  The BugLady, who thinks 73 degrees is hot, was not a happy camper.

2012 – The BugLady found this handsome dragonfly at a local Nature Preserve a few days ago.  Her photographic philosophy (necessitated by her hyperopia) is “Snap First and Identify Later;” so she appreciated the beauty of this spiffy individual in the moment (with a few soft “Wows!”).  She kept thinking, as she stalked the dragonfly on that fine, April day, that it sure looked like a meadowhawk, and it flew like a meadowhawk (and Wisconsin just doesn’t have that many red dragonflies), but that meadowhawks were not due on the landscape for months.  She appreciated it even more when she discovered later that she was looking at a new (for her) species – a Variegated Meadowhawk. 

When the BugLady wrote her BOTW about Meadowhawk Dragonflies in the summer of 2009 https://uwm.edu/field-station/meadowhawks/, she hadn’t seen a Variegated Meadowhawk (Sympetrum corruptum).  Sympetrum means “with rock” and may refer to the rocks and other substrates that meadowhawks perch on to gather heat early in the day.  Generically, adult meadowhawks (in the Skimmer family Libellulidae) may be found hunting away from water or hanging around the shores of the lakes and ponds where they will deposit their eggs in late summer.  Instead of hatching right away, eggs of resident meadowhawk species spend the winter in a state of suspended animation called diapause and put off hatching until spring. 

Meadowhawk naiads (young) are hooked and spiny, though Variegated Meadowhawk naiads have very few hooks or spines on their exoskeletons.  They feed underwater for a few months on aquatic invertebrates, and maybe on a few tiny tadpoles and fish, until one fine evening when they crawl out of the water to complete their transformation into adults.  Some meadowhawk species in cold northern waters are naiads for a few years.   

Adult meadowhawks may chase their insect prey while in flight, but they’re more likely to spot it from a perch and take off after it, flycatcher-style.  The naiads sprawl on their underwater substrate and wait for prey to present itself.

VARIEGATED MEADOWHAWKS have tweaked the meadowhawk model a bit. 

The first word Paulson uses to describe Variegated Meadowhawks in Dragonflies and Damselflies of the East is “Robust” – their abdomens are much chunkier than those of other meadowhawks.  The medium-size body (about 1 ½”), patterned abdomen (possibly the reason for “corruptum,” which comes from a Latin root meaning “to break”), tinted veins on the leading edge of all four wings, stigmas (pigment dots at the wing tips) that shade from pale to dark to pale, and yellow spots on the sides of the thorax are all marks of a Variegated Meadowhawk.  Where the male has red markings that become more solidly red with age, the female and the newly-emerged juveniles are golden.   

Compared to other meadowhawks, they spend more time perched horizontally on and near the ground, and males are more territorial. 

They are early meadowhawks.  While most of their meadowhawk cousins appear in July and fly through the first frosts, Variegated Meadowhawks arrive, as this one did, as early as mid-April.  Legler, in Dragonflies of Wisconsin, says that “hot days in spring with southerly winds bring them into the state.”  In some parts of their range, they are the first dragonflies on the scene; here, they arrive at about the same time as the first, migratory Common Green Darners. 

These are migratory meadowhawks that migrate close to the ground and navigate visually, using the position of the sun.  They repopulate the North Country from the south and southwest in spring – they are far more common on the other side of the Mississippi and are considered vagrants or migrants east of the Big River.  Variegated Meadowhawks have been recorded in 43 states plus the southern tier of Canada https://bugguide.net/node/view/6538/data and in about half of Wisconsin’s counties, but much of the time, they’re just passing through.  Sightings peak around their spring arrivals and their mid-summer departures.   

Do they go back where they came from at the end of their season here? 

They do not.  Joined by other Variegated Meadowhawks that have drifted into the state from the west, the offspring of the Variegated Meadowhawks that stopped to breed here in April will head toward the Atlantic when they depart in late August.  They leave no young overwintering in Wisconsin ponds.  They migrate, often in the company of darners and saddlebags, south along the East coast as far south as Honduras and Belize (they also occur, inexplicably, in Southeast Asia) https://www.xerces.org/sites/default/files/2018-05/12-036_01_MDP_Field_Guide_4-4-2013Websec.pdf.  

The next generation heads north in spring immediately after becoming adults.  Most Variegated Meadowhawks seen here in spring are adults, and most fall migrants are juveniles.  It has been suggested that this migratory habit could give Variegated Meadowhawks an edge during a period of climate change. 

Mead, in Dragonflies of the North Woods, warns us against attempting to show off our netting skills by capturing a Variegated Meadowhawk, “as they may make a fool of you. This is one of the most difficult dragonflies to net; it is very shy and wary (and seems to possess a level of telepathic ability).”

Nota Bene: The most common butterfly on the BugLady’s landscape these days, the Red Admiral, is also a migrant to these parts.  Red Admiral, Painted Lady, and American Lady butterflies, all in the wandering genus Vanessa, are cold-intolerant.  They return to our area in spring, and some years see huge population booms and mass migrations.  You can report spring migration sightings at: http://vanessa.ent.iastate.edu, where you can also find out some neat stuff about Red Admiral behavior. 

There are a lot of Red Admirals around in 2023, too.

2012 Go outside – it may be early; it may be eerie; but spring’s happening.

Kate Redmond, The BugLady

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

Bug o’the Week – Birch Catkin Bug by Kate Redmond

Bug o’the Week
by Kate Redmond

Birch Catkin Bug

Howdy BugFans,

When the BugLady started this little project in the summer of “twenty ‘aught seven,” she had two criteria for candidates for the bug of the week – that she had taken a decent picture of the bug, and that she was able to find an interesting story about it.  Today’s episode sets the bar pretty low for picture quality.

This adventure started with a (very) bad photograph.  Last week, the BugLady headed to a little bog that she frequents so she could test drive her new macro lens.  She photographed the spiffy male catkins of an alder, and then she aimed the camera overhead at a cluster of last year’s female cones, just to see what the lens would pick up.  A “throwaway shot.”  When she put the picture up on the screen that evening she realized that the camera had seen a bunch of small bugs that she had not, and although she massaged the image, it was still pretty sad.  So she went back the next day – with much the same result.  That’s how it goes, sometimes, but here are some splendid pictures of the bug: https://www.britishbugs.org.uk/heteroptera/Lygaeidae/kleidocerys_resedae.html.

The first thing she noticed on Trip #2 is that although she checked the cones on alders all along the boardwalk, she only saw the bugs on alders that grew fairly close to the shoreline of a small, adjoining lake.  The second thing she noticed is that these bugs are slippery little devils – when she gently hooked the branch of a tall alder to bring the cones down to camera level, the bugs had vanished by the time the cones got close.  The third thing she noticed is that this was a bug that she’d never seen before (a “True bug” in the Order Hemiptera, and the suborder Heteroptera, because of the “X” arrangement of the folded wings on the back). 

Brief, slightly technical digression (but it’s spring, but our brains are yawning and stretching and greening up, and we’re up for this):  Once upon a time, there was an insect order called Homoptera, which included cicadas, leafhoppers, spit bugs, scale insects, aphids, and the like.  A separate order, Hemiptera, was called the “True Bugs,” and it included stink bugs, leaf-footed bugs, assassin bugs, seed bugs, etc. – the guys with the X’s on their backs.  The two Orders were merged, under the umbrella of “Hemiptera,” and the true bugs are now in a suborder called Heteroptera (which means “different wings,” because their front pair of wings is leathery at the base and membranous at the tip).

BIRCH CATKIN BUGS (Kleidocerys resedae) are in the suborder Heteroptera and in the Seed Bug family Lygaeidae – “Seed bugs” because most family members (like Milkweed bugs) feed on seeds, puncturing them with piercing mouthparts.  Due to the chemicals they pick up from the plants they eat, many Lygaeids don’t taste so good, and some (like Milkweed bugs) are clad in bright colors to advertise that fact.  Most Lygaeid species also have stink glands, and so the term “stink bug” may be applied pretty loosely, but the Hemipterans that are officially called Stink bugs belong to the Stink bug family Pentatomidae.  Birch catkin bugs have an odor that some people call strong and unpleasant, but that blogger Larry Hodgson, the Laidback Gardener, described as “intense, with a hint of wintergreen.”

The BugLady was surprised to learn that this little bug’s range is Holarctic, a term that refers to much of the Northern Hemisphere, around the globe.  It didn’t come over on the boat – it’s native to northern portions of both the Old World (the Palearctic) and the New (the Nearctic) https://bugguide.net/node/view/100506/data, and it’s never far away from its host plants in the genus Betula – the birches.  The BugLady found some good information about it on nature sites in the United Kingdom. 

If you figure that a mature alder cone is about two-thirds of an inch long, you can see that these are very small insects, indeed – maybe 3/16” long, max.  They are generally rusty-colored, with clavate (clubbed) antennae, and they’re “densely punctate” – covered with small pits or punctures https://bugguide.net/node/view/1598589/bgimage. https://bugguide.net/node/view/1440751/bgimage https://bugguide.net/node/view/524365/bgimage https://bugguide.net/node/view/168566/bgimage    

Birch catkin bugs eat birch seeds, which are found in the female catkins/cones.  Although the nymphs have a strong attachment to their birch host plants, adults do use other trees and shrubs, like the Ericaceae (heathers and blueberries) and the Rhododendrons; bugguide.net lists “alder, and other deciduous trees/shrubs” among the adult food plants.  The BugLady guesses that the bugs she saw were looking around for any of last-year’s seeds that may have weathered the winter within the cones, since the new alder cones won’t be producing seeds for a while.

They overwinter as adults, sheltering in old, fallen catkins and in leaf litter (though in some areas where there are several generations per year, nymphs may also overwinter).  They wake in spring and mate in June, and according to several sites from the United Kingdom, “whikst [sic] flying they emit a vocal mating calls using a strigil [a comb-like scraper] located on one of the hind wing veins.”  Females lay eggs on old, female birch cones. 

THE RABBIT HOLE DU JOUR: The BugLady was curious about the statement about Birch catkin bugs emitting mating calls in flight.  Rubbing two body parts together to produce sound is called stridulation, and it isn’t uncommon – think locusts and katydids – but it’s not universal, either.  Milkweed beetles stridulate, and Hemipterans like tree hoppers do, too, and depending on the species, adults, larvae, and even pupae may stridulate.  Here’s what she learned from a wonderful (and very scholarly) paper in Biological Reviews called Sexual selection and predation drive the repeated evolution of stridulation in Heteroptera and other arthropods, by L. Davranoglou, G. Taylor, and B. Mortimer.  

  • Kleidocerys makes noise by striking a file on the wing against a scraper on the thorax (Another reference said that both male and female Kleidocerys “sing,” and they produce the same song).
  • The main ways arthropods generate vibroacoustic signals is by stridulation.
  • Stridulation is often used by species that live in/on soil, leaf litter, plants, and water.
  • Stridulation seems most often to be associated with defense and with courtship/mating (or with a combination of the two). 
  • The body parts that are used as stridulatory organs are often those used in grooming, and grooming is a common part of courtship and mating rituals.
  • BUT (emphasis, the BugLady) – most Heteroptera don’t have tympanal organs (“ears”)!  When they make sound, they can’t hear it – at least not as we define hearing – but can probably perceive/”feel” it as vibrations through the substrate, the surface they’re living on.  If the stridulation is defensive, then their predators can probably hear it. 
  • As a group, aquatic bugs like water boatmen, giant water bugs, backswimmers, water scorpions, etc., do have tympanal organs (and some have tympanal organs but they don’t stridulate, a story for another day). 

Cool paper.

Are they pests?  Since they mainly feed on the seeds, there may be a very slight cosmetic impact if catkins turn brown, but few of us plant birch trees for the seeds.  There were several accounts of big infestations where Birch catkin bugs ran out of catkins and nibbled on birch leaves late in the season and marched across the landscape (with a few accidentally coming inside homes, where there’s nothing for them to eat, so they die) (crushing the intruders is not advised).  They are said to gather on warm, exterior walls on fall days, like box elder bugs, but even though some accounts list them as “common,” most people (like the BugLady) have never noticed them.  The Minnesota Seasons website says that “Based on the number of reported sightings, it is relatively uncommon in Minnesota. However, it is probably under-reported due to its small size.” 

Go outside – find a wetland!

Kate Redmond, The BugLady

P.S.  THEY’RE COMING!  The BugLady loves interactive maps.  Be sure to set the map for 2023: https://maps.journeynorth.org/map/?year=2019&map=monarch-adult-first.

Bug of the Week archives:
http://uwm.edu/field-station/category/bug-of-the-week/

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