Bug o’ the Week – Snipe Fly

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Howdy, BugFans,

Flies (which we tend to view as mangled objects at the business end of a flyswatter) belong to the large order, Diptera (“two wings”) – 100,000-plus species have been described and probably another 100,000-plus species are waiting in line for scientific attention (one out of every ten animals is a fly) (and one in every five living things is a beetle).  Members of the order are remarkably diverse (and isn’t the Class Insecta a grand study in variations on the theme of three body parts, six legs, and maybe some wings!).  Flies come in all colors, with a variety of body shapes and leg lengths, and some have astonishing eyes, but the word “beautiful” is seldom applied to them.  Except in early summer when the Gold/golden-backed snipe flies are in flight.

It is thought that snipe flies (family Rhagionidae) got their name from some imaginative entomologist who believed that the rather prominent proboscis that adorns some species looked like the bill of an avian snipe (and for BugFans who once endured some hazing in the classic form of a “snipe hunt,” there are, indeed, avian snipes).  SFs tend to be found on vegetation in damp, shady places, where they often perch head down; they’re slow flyers that happily dart off on foot when alarmed.

Adult SFs are long-legged with a round head and a tapering abdomen, and many are patterned.  They have piercing mouthparts that they may use to prey on other insects (mainly smaller flies) or to grab a blood meal from a variety of vertebrates.  Members of one SF genus (Symphoromyia) are merciless pests of bison in summer, when the bison are vulnerable because they’ve shed their thick coats.  In the West and in parts of the eastern US, females of some species bite humans.  The BugLady inhabits snipe fly habitats regularly and has never seen one on her skin.

The larvae (maggots) of some species of SFs are aquatic, but most others can be found in moist soil or moss or decaying logs.  They are carnivores, and in aid of that, the larvae of some western SFs do an “ant-lion” thing (and so are called “worm-lions”) – digging cone-shaped pits in slippery sand/dust and then lurking at the bottom, waiting for insects to drop in for supper.  In the “Man bites Dog” category, snipe fly egg masses were, according to one source, collected, cooked and eaten by some Native Americans.  

GOLD(EN)-BACKED SNIPE FLIES (Chrysopilus thoracicus) (Chrysopilus means “golden hair” and thoracicus refers to the thorax) ply the tall grasses, sedges and thickets around wetlands east of the Great Plains.  Look down – the BugLady rarely sees them higher than two feet off the ground.  With their striking gold thorax, white chevrons on the abdomen, and smoky, patterned wings, these half-inch flies are an eyeful.  Speaking of eyes, a male SF’s are much larger than the female’s.  There are 30-some members of the genus in North America, and the GBSF is the most dramatically colored.  Some sources consider them to be wasp-mimics, but the BugLady doesn’t see it.

GBSFs are predators on aphids and other small insects.  Their eggs are laid in bunches in leaf litter and at the soil surface, and their larvae feed on small invertebrates that they find in moss or decaying wood.

Since the GBSF has always been the BugLady’s mental image of “Snipe fly,” it took her a while to realize that the brownish fly with spotted wings was also a snipe fly, the COMMON SNIPE FLY (Rhagio mystaceus) (probably).  Because of their habit of surveying the world while perched head-down. a number of Rhagio snipe flies are called “down-looker flies.”

For a fly whose “first name” is “Common,” there’s not a lot of information out there about the CSF.  There are 25 species in the genus in North America.  CSFs seem to follow the general SF game plan; their predatory larvae feed on small invertebrates in moist soil.  Internet hits do include species lists from the United Kingdom.

The BugLady

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