Bug Lady Blog: Headless Moths I – the Cattail Borer

Salutations, BugFans,

This Cattail Borer moth showed up in mid-June, another species for the BugLady’s porch light list.  It’s a handsome moth, and another example of a moth that would be hard to identify in a moth book (like the BugLady’s venerable Moth Book, by Holland) that only shows moths with their wings spread open.  Attitude is everything.

Cattail Borer Moths (Bellura obliqua) are in the Owlet moth family Noctuidae.  There are a half-dozen or so species in the genus Bellura in eastern North America, and according to the Peterson moth guide, they might represent a “species complex,” a continuum of very closely-related, yet distinct, species that differ little in appearance or genetically.  Some members of a species complex may be similar enough that they can hybridize, and the fluidity of relationships within a species complex is thought to be an example of speciation – the development of new species – in action.  Not surprisingly, one source said the genus is “in need of revision.”

They’re in the tribe Azamini, which are called “Divers” because their “semiaquatic” larvae http://bugguide.net/node/view/100959/bgimage feed on/in leaves and stems of emergent aquatic plants like cattails, arrowhead, pickerelweed, water hyacinth, bur reeds, water lilies, and even skunk cabbage (the BugLady is always surprised to hear “semiaquatic” in the same sentence as “Lepidoptera”).  They bore in and create galleries in submerged portions of stems, and they also feed on leaves.  One source said that under the right circumstances, the cattail borer could be cannibalistic, and despite their concealment, a few parasites are able to find them.

Larvae are frequently found with their heads in the water, breathing through modified spiracles (breathing pores).  According to Ellen Robertson-Miller’s paper called “Observations on the Bellura” (1922), “A kind of turret – the frass of the larva – about the opening in the leaf usually indicted that a Bellura was living below;…..I removed and examined one of the caterpillars…..The dorsal half of the twelfth segment seemed to have been sliced away, leaving exposed a posterior area on the eleventh segment, where the caudal spiracles, transposed from their normal side position, were located.  These were larger than the other spiracles.  This specialized breathing mechanism for Bellura caterpillars may have required long years in its perfecting, but how clever it is!  A larva can stay concealed all day in the stem of its water plant, just backing to its entrance when its air reservoirs need refilling, or it can remain submerged for hours…”

Ms. Cattail Borer lays her eggs in a frothy/silken/hairy mass within about 12” of the tip of a cattail leaf – Robertson-Miller likens the egg case to a spider egg sac.  The larvae hatch and feed on the chlorophyll-bearing tissues of the leaf, then bore downward into it as far as two feet.  They eventually exit by chewing a hole in the leaf, and then they enter the stem.  When they’re ready to pupate, they emerge from their plant stem (often below the water’s surface), pop up to the surface, and swim for shore by undulating their abdomens.  Robertson-Miller observed “because of the ease with which these Bellura swam through the water, I thought they might pupate on shore in the ground,” and when she supplied them with cans of soil, they did (in nature, they crawl under leaves, soil, bark, debris, or rotting wood).

The cattail borer may or may not be a pest, depending on whether you’re trying to grow cattails or trying to get rid of them.  In the mid-1980’s, Minnesota was testing cattails as a potential plant to cultivate as a biofuel.  One study found that the Cattail borer can reduce cattail productivity because the plants put lots of energy into replacing damaged leaves at the expense of extending the rhizomes, but another concluded that there was little impact from cattail borer grazing.

Cattail borer larvae were among a number of larvae tested for winter hardiness by James S. Hine, who reported on his research in The Ohio Naturalist in 1908.  Overwintering larvae were collected from stems of cattails during the frigid winter of 1893.  They were exposed to overnight temperatures of -2 to –17 degrees Fahrenheit – some in jars of water, and others unprotected, and they were subjected to repeated thawing and refreezing.  “None of the specimens snowed signs of injury from the treatment,” wrote Mr. Hine. “Larvae collected just after daylight on January 20, when the thermometer registered —15 could be snapped in two almost like icicles and crystals of ice were observed within their body cavities. Some of these pieces were alive when thawed out at the end of a week.”  He quotes a paper by P. Bachmetjew in “Zeitschrift fur wissenschaftliche Zoologie” in 1899: “The thawing out of insects after their body fluids have been frozen has no noticeable influence upon their return to life, but only upon the intensity of their vitality.”

As mammologist William Hamilton at Cornell used to say, you don’t have to go to exotic lands to study animals, there’s plenty to discover in your own back yard.  Check out “The Backyard Arthropod Project,” http://somethingscrawlinginmyhair.com/2013/03/09/cattail-borer/ whose author’s mission is to “document every arthropod that I can find on our property – about 9 acres on the north slope of Old Mill Hill in the Keeweenaw Peninsula of Upper Michigan” (a man after the BugLady’s own heart).  He figures he has decades of material in his back yard.

The Cattail Borer’s full appellation is Bellura obliqua (Walker, 1865).  The BugLady was curious about the scientist who described and named this moth, so here is the third in the occasional sidebar series “Who Were Those Guys??”

Francis Walker (1809 – 1874) is a terrific example of how things can go south, professionally.  Born into a wealthy British family, he was blessed with an early and avid interest in Natural History.  He loved to travel, especially in the mountains, was an inveterate collector, and he contributed many specimens to the prestigious museums of his time.  He was a member of the Entomological Society of London, which was founded in 1833 to be a meeting of “gentlemen and friends of entomological science,” and which admitted women as equal members.

In 1837, Walker was hired by the British Museum to catalog its insect collection, a job he held for the next 25 years.  He was a prolific worker who published more than 300 scientific papers, notes, and catalogs.  The volume of his work was immense, and his literature research was thorough.

So, what was the problem?  During his employment as curator at the Museum, Walker described some 46,000 insects, 10,000 of which were new.  With numbers like that, his work was, inevitably, superficial.  In an era where the rules of taxonomy were not yet firmly set, many of his peers felt that his science was “iffy,” and that he chronically described, named, re-described, and renamed the same species and variants of the same species (although the rumor that he was being paid a shilling per new species and a pound per new genus was not true).  For example, of the 222 new members he added to the Cicada family, only 138 are considered kosher today.  Biographers can’t say why he was singled out for criticism, when others’ methods were similar, but he presented an enormous target.

The author of an anonymous obituary published in the Entomologist’s Monthly Magazine in 1874 wrote, “More than twenty years too late for his scientific reputation, and after having done an amount of injury almost inconceivable in its immensity, Francis Walker has passed from among us.”  Ouch!

Criticisms that began during his lifetime turned into a feeding frenzy after his death.

  • This kind of work needs no comment—it sufficiently condemns itself.” (Butler, 1894)
  • In 1894, the practice of assigning many names to a single species was called Walkerism.
  • Walker described the specimen, and not the species, the characters of which he was generally incapable of grasping,” (Austen, 1907).
  • To one who has examined Walkers types, it will be a surprise that so great a degree of accuracy has been obtained, for many of the typical specimens in the British Museum, described by Walker, are so badly denuded that they ought never to have been described at all” (Fernald, 1881).

The vitriol was not universal – Walker had his apologists, and even some colleagues who condemned him professionally appreciated his kindness and generosity.

  • He was one of the quietist and gentlest of men; his sensitive nature was much pained by some of the harsh criticisms that were passed upon his work.  His mistake was in attempting too much.  Had he confined himself to the Diptera, his reputation would probably never have been impaired.” (Smith, 1891).
  • Even those who felt most keenly the disrepute into which he brought the entomological section of our great Natural History Museum, will miss with regret his courteous salutation and simplicity of manner.” (Anonymous, 1874).
  • His friend Edward Newman wrote posthumously that “Throughout my long life I have never met with anyone who possessed more correct, more diversified, or more general information, or who imparted that information to others with more readiness or kindness; I have never met with anyone more unassuming, more utterly unselfish, more uniformly kind and considerate to all with whom he came in contact.”

Kate Redmond, The BugLady

Bug of the Week archives:
http://www4.uwm.edu/fieldstation/naturalhistory/bugoftheweek/

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