Wasp Wednesday: Wasp Workshop

I recently had the privilege of leading a wasp identification workshop at the ultra-modern Eulett Center in Adams County, Ohio. The ten participants arrived Friday evening, August 26, at the nearby rustic lodge known as Rieveschl Chalet. Both facilities are run by the Cincinnati Museum Center, though The Nature Conservancy also occupies offices in the Eulett Center and the two organizations co-manage the Richard and Lucile Durrell Edge of Appalachia Preserve System.

All my “students” were enthusiastic and energetic in the field and in the lab. I gave an introductory lecture on selected wasp families at the Chalet on Friday night, and we looked forward to seeing actual living specimens in the rural and prairie habitats the next morning.

There are never any guarantees that one will actually find wasps just by looking, but my hosts Chris Bedel and MarkZloba and myself scouted out some nearby areas ahead of time on Friday. That paid off. The participants got to see the Katydid Wasp, Sphex nudus, nesting in the dirt floor of an old barn. We even witnessed one of the wasps fly in with her prey, a Carolina Leaf-rolling Cricket (Camptonotus carolinensis).

We also discovered caterpillars of the Catalpa Sphinx moth, Ceratomia catalpa, covered in the cocoons of the parasitic braconid wasp Cotesia congregate. These and other wasps we observed will be topics in future “Wasp Wednesday” posts, and images shared on my Flickr Photostream.

We convened at the Eulett Center for lunch, then went back out for a more field time at another location. There we collected cuckoo wasps (family Chrysididae), and observed a mating pair of thread-waisted wasps, Eremnophila aureonotata. Inside a barn we saw many old nests of the Pipe Organ Mud Dauber, Trypoxylon politum, and an active nest of the Northern Paper Wasp, Polistes fuscatus. When wasps were not to be found, the sharp eyes of the group spied many other insects including bizarre caterpillars like the “Monkey Slug.”

The late afternoon was spent attempting to learn the complicated anatomy of wasps, and introducing “keys” as a way to identify wasps to family, genus, and sometimes species. Traditional keys are dichotomous, meaning that they are composed of a series of couplets. One reads each couplet and decides which of the two lists of characters corresponds to their specimen, then proceeds to the next indicated couplet. Eventually, this process yields a name instead of another couplet. Interactive keys are a product of internet technology whereby the user checks boxes that correspond to their specimens, then hits the search button to whittle down the possibilities.

Chris Bedel, in addition to having a wealth of knowledge about the local flora and fauna, is a fabulous cook. Dinner on Saturday night was healthy and delicious: Pasta with artichoke hearts, cherry tomatoes, black olives, chicken, and spices, plus a mixed greens salad, garlic bread, and brownies and ice cream and strawberries for dessert choices.

After dinner we played a game I invented called “Wasp/Not Wasp,” whereby students view two images on one PowerPoint slide. They must determine which is the wasp, and what the other insect imposter is. I complicate matters by sometimes showing two wasps, or two non-wasps. The whole thing seemed to be a hit, and most of the time everybody got the answers right.

I concluded the evening with a short lecture on wasp sleeping behavior.

Sunday morning found us afield again, this time in the Lynx Prairie unit of the preserve system. Mark Zloba had set up an enormous malaise trap days before, to help secure wasp specimens. A malaise trap is a tent-like structure designed to intercept flying insects. The “bugs” then try to fly over the barrier. Instead they are funneled to the highest point (at both ends of the trap in this case) where they drop into a container with a killing agent. This trap is often one of the few ways one can capture certain kinds of Hymenoptera, and indeed the diversity just in the one sample was amazing.

Before we knew it, the morning was over and it was lunchtime. After a leisurely meal, the students slowly departed to resume their normal lives, as if having an interest in nature and insects means you have a “normal” life. I had a great time seeing friends I haven’t seen in decades, meeting Facebook friends, and making new friends that I know will be lifelong colleagues.

Special thanks go to Stephen Pelikan who drove me out to the Eulett Center from the Cincinnati International Airport. Chris and Mark were exceptional hosts that made me feel instantly at home. They made modest demands, and allowed me ample time to explore on my own.

Do consider attending Advanced Naturalist Workshops like this, or simply visiting the Eulett Center on your own. They always welcome visiting naturalists, researchers and scientists who give them ample warning.

Spider Sunday: Crevice Weavers

Perhaps no spiders are more often misidentified than the “crevice weavers” in the genus Kukulcania, family Filistatidae. They are quite common throughout the southern United States, where they are frequently confused with everything from brown recluse spiders to tarantulas.

There are currently five species and one subspecies of Kukulcania recognized in the U.S. Here in Arizona we have both K. arizonica and K. hibernalis (the “Southern House Spider”). Indeed, houses are often where you find them. Look for their sprawling, lacy webs issuing from the exterior of window frames, under the eaves, and similar situations.

Filistatids in general belong to a larger group of arachnids called “cribellate” spiders. These spiders possess an extra silk-spinning organ called a cribellum, and a comb on the outside of the metatarsal segment of each fourth leg. This row of short, stout, curved hairs is called a calamistrum and is used to “fluff” the silk that issues from the plate-like cribellum. This “carding” of silk is accomplished by very rapid vibration of the fourth leg as it rests on the third leg. This is in contrast to most other cribellate spiders that employ a slow rocking motion. The web that results is therefore not sticky, but the threads so random that they easily entangle potential prey.

The odd web is just the beginning of weird for Kukulcania crevice weavers. The genders differ so dramatically in appearance that one can be forgiven for assuming they are different species. Mature females are a lovely, velvety black or dark gray in color, with a body shape and lumpy eye arrangement reminiscent of a tarantula. Mature males are beige or pale brown in color, with small bodies and extremely long legs. They are mistaken for brown recluse spiders much of the time, but note the differences. Male Kukulcania have eight eyes, grouped atop the crown of the head as they are in the female. Recluse spiders have only six eyes, grouped in three pairs across the front edge of the carapace. Also notice the extremely long, elbowed pedipalps of the male crevice weaver. No recluse spider is that….well,…well-endowed.

We’re not finished, it gets stranger. All filistatids known thusfar have their jaws (chelicerae) fused. That means that each one of the pair is incapable of moving independently, like in most other spiders. They are also built to lose their legs if necessary to escape a predator. Actually, many kinds of spiders possess the ability to break off parts of their legs without losing much blood in the process. This phenomenon is known as “autospasy,” and in the case of crevice weavers the weak joint is at the juncture of the tibia and patella segments.

Interestingly, female Kukulcania continue to molt after they become adults. Mygalomorph spiders (tarantulas) are the only other spiders known to do this. It seems to be related to longevity: both spiders take a long time to reach sexual maturity, and are capable of living several years. Like the cellar spiders I addressed in an earlier blog entry, filistatids are “haplogynes,” meaning that the females have largely unmodified, if not non-existent external genitalia. The paired openings to her reproductive tract are under what is more-or-less a slot-like orifice.

The best time to observe Kukulcania species is after dark. Females will venture to the lip of their retreat in anticipation of prey. Males will be wandering in search of love and romance. See if you can’t find one or both of the sexes on the exterior of your own home, garage, shed, or barn.

Wasp Wednesday: Pimpla sanguinipes

I should know by now that nothing comes easy in entomology. Here I figured I could just whip out a short piece on an ichneumon wasp I imaged in southern California back on March 26, but no-o-o-o, it looks like even the name I have for it, courtesy of Bob Carlson via Bugguide.net, might be outdated. Meet Pimpla sanguinipes, or whatever alias it goes by these days.

Actually, it looks like the appropriate name for this member of the family Ichneumonidae is Coccygomimus sanguinipes. Bugguide lists Coccygomimus as a “synonym” for Pimpla, so maybe it still *is* Pimpla.

The wasp I found at the salt marsh preserve in Carpenteria is further defined by the subspecies name erythropus. I do wonder what all these references to “blood” mean, though the wasp does have reddish-orange legs.

Dr. Carlson pointed out the complexity of all this in a personal communication with Vasile Bagazzoli, a volunteer editor at Bugguide:

"erythropus and sanguinipes might really be two separate species, judging from the fact that they occupy different habitats: sanguinipes in arid areas and erythropus in forested areas. Townes even had differences in punctation for the two. His concept of subspecies was very dubious, and he did not strictly apply the concept in a geographical sense and named many sympatric subspecies, many of which I relegated to synonymy in the 1979 catalog. But this case was different, and I might have just elevated the two taxa to species level but did not. I don't remember if I had a reason for not doing it, but maybe it was because there was a dearth of specimens in the National Collection from which I could form an opinion."

Dr. Carlson is retired from the Systematic Entomology Laboratory at the National Museum of Natural History in Washington, DC. He also studied under the “grandfather” of ichneumon taxonomy, Henry T. Townes.

Ok, back to the actual wasp, and what *it* does for a living. The species ranges west of the Rocky Mountains from Idaho to New Mexico and west to the Pacific coast including British Columbia and southern California.

Females seek out moth caterpillars in which to lay their eggs. Their hosts include tent caterpillars (Malacosoma spp.), buck moths (Hemileuca sp.), the Virginia Tiger Moth (Diacrisia virginica), the Douglas Fir Tussock Moth (Orgyia pseudotsugata), Western Tussock Moth (O. vetusta), Coddling Moth (Cydia pomonella), Genista Broom Moth (Uresiphita reversalis), Gooseberry Fruitworm (Zophodia convolutella), Barberry Geometer (Coryphista meadii), the Oak Looper (Lambdina punctata), and two other geometer moths (Eucaterva variaria and Prochoerodes forficaria). Several of these moths are abominable pests, so this generalist parasite is a welcome friend to agriculture and forestry.

The physical dimensions of this wasp don’t fit its superhero reputation. Females range between 10.5-12.5 millimeters in length, males around 8.5 mm. The black body, orange legs, and short, stout ovipositor help to identify the species fairly easily. We just can’t decide what name to call it.

Spider Sunday: The Cross Spider

’Tis late summer, now, in most parts of North America, anyway, and orb weaver spiders are becoming more conspicuous as they mature into large adult specimens and spin bigger webs (soon to be revealed by falling autumn foliage). Among the most abundant of these spinners is the “Cross Spider,” Araneus diadematus.

The Cross Spider is a European immigrant, just like most of us human residents of the U.S. and Canada, so the species feels most at home in northern climes. It is recorded from Newfoundland and Nova Scotia to British Columbia and south to northern California, Michigan, Ohio, Pennsylvania, New York and Rhode Island. It is plenty accustomed to people, too, so it is a regular occupant of gardens and yards in urban areas.

Araneus diadematus gets its popular English name not from an angry disposition, but because it usually sports silvery-white dots that form the pattern of a traditional Christian cross on its abdomen. This is a relatively consistent marking, but as with most orb weavers, there can be exceptions. The spiders usually hang head-down in the very center (hub) of their webs, but sometimes an individual spider may be more reclusive, and connect herself to the web via a bundle of “signal threads” that run from the hub to her hiding place in a rolled-up leaf or other nearby retreat.

The reaction of homeowners to the presence of this and other species of orb weavers runs the gamut from curiosity to consternation. No species of orb weaver is known to be dangerously venomous to people or pets, so there is no reason to fear them. The spiders themselves will literally shake at the close approach of a person or other large animal, vibrating their web and no doubt startling the inquisitive visitor. Should that tactic fail, most orb weavers drop abruptly from their web, anchoring a dragline to the hub so they can climb back up once danger passes.

This species happens to include some real celebrities. No, seriously. “Anita” and “Arabella” were two female Cross Spiders sent into space on Skylab 3 in 1973 to study the effects of zero gravity on web construction. Prior to that, several specimens were used as guinea pigs in the study of how psychoactive drugs affect spiders’ ability to spin webs. Those experiments were first conducted by a German scientist beginning in 1948, then repeated by NASA scientists in 1984. For an absolutely hilarious send-up of that research, you must see ”The Wood Spider” video on YouTube. I take no responsibility for laughter-induced fatalities.

An adult female Cross Spider has an average body length of about 13 millimeters, though gravid females certainly appear larger. Like the story of Charlotte’s Web, each spider’s life from egg to adult spans only a year. Enjoy their handiwork and pest-controlling services while you can.