Wasp Wednesday: Early Mentors

I may have started collecting wasps because no one could call me a sissy for catching something that can fight back, but I owe my continued fascination with these insects to a number of amazing mentors who showed me there is much more to hymenopterans than I ever imagined.

One of the entomologists I most admire is the late Howard Ensign Evans. Not only was he a world-class authority on Hymenoptera, but one of the most eloquent writers and “popularizers” of entomology that I have ever read. His classic Life on a Little-Known Planet is without a doubt the best introduction to insects for a general audience as has ever been published. Evans managed to maintain a passion for, and awe of, the natural world untarnished by the efforts of academia to reduce all to “models,” statistics, and biochemical reactions.

I also read Evans’ Wasp Farm, and The Pleasures of Entomology. His book Wasps, co-authored with Mary Jane West-Eberhard, was my wasp bible for many years. Mary Jane wrote an amazing and comprehensive biography of Dr. Evans that does his contributions to science and literature vastly more justice than I ever could here.

I will always treasure a piece of correspondence I received from Dr. Evans in January of 1984 after I had written him for advice on how to make a living writing. He suggested that I would need “another means of support.” His sense of humor is another admirable quality.

Just last month I picked up Evans’ A Naturalist’s Years in the Rocky Mountains, which should serve me well in getting to know the fauna, flora, and seasons of my new Colorado Springs home.

Once I got to college at Oregon State University, I had the good fortune to become acquainted with Dr. George R. Ferguson. He was a taxonomist of the highest degree, working mostly on the genera Cerceris and Eucerceris, finishing what his friend and colleague the late Herm Scullen had started. Dr. Ferguson still found time to take me under his wing, providing many identifications for my growing collection.

I’ll never forget the time I eagerly presented a small series of metallic blue sphecid wasps for his appraisal. He took a quick look and determined they were the Blue Mud Dauber, Chalybion californicum. I sighed and said that I thought they were the Steel Blue Cricket Hunter, Chlorion aerarium. He plucked out one specimen, stuck it under his microscope, and replied “Well, I’ll be, you’re right. They’re awful small, though.” He was right, too: they were males, and not particularly impressive examples of that gender, either.

Dr. Ferguson has since passed away as well, but I am delighted to report that his legacy lives on in the form of an endowment fund at OSU, which grants funding annually to outstanding undergrad and graduate students majoring in entomology there. I would expect nothing less from my most kind and generous mentor.

More than what these two men taught me about Hymenoptera was what they taught me about being a man and a human being. I hope I can be half as courteous and helpful to those who ask for my help. I hope I can be a positive and inspirational example to the students and scholars of tomorrow.

Spider Sunday: Spider Enemies

Spiders may seem invincible, especially to those who fear them. Not true. Spiders are under constant threat from predators, parasites, and other mortality factors. It is impossible to even list all the agents that kill spiders, but some creatures that prey exclusively on spiders, or nearly so, are worth investigating.

Even tarantulas, the largest spiders, are not immune to attack. Enormous wasps in the genus Pepsis aggressively seek these gargantuan arachnids. Only the female wasp is armed with a stinger, a formidable weapon to match the spider’s fangs.

In the southwest U.S., the wasp fuels her superhero lifestyle on nectar, especially from milkweed flowers. Once juiced-up, she scours the ground for signs of her prey. Encountering an inhabited burrow, she lures the spider out of it and the battle begins. Tarantulas can move fast when they have to, but the wasp is usually quicker. She stings it in a nerve center on the underside of its cephalothorax, rendering the arachnid almost instantly paralyzed.

Once she has immobilized the spider, the wasp drags her victim to a hole where she caches it. She sometimes uses the spider’s own burrow. She lays a single egg on the spider, then leaves. She will repeat the process until she dies. The larva that hatches from the egg consumes the still-living spider, eventually pupating and emerging as an adult wasp the following year.

All wasps in the family Pompilidae, including Pepsis, are dedicated spider-slayers. So are mud daubers in the families Sphecidae and Crabronidae. The Black and Yellow Mud Dauber, Sceliphron caementarium, builds clod-like mud nests under the eaves of houses and other buildings, stocking each cell with numerous spider victims. The wasps are generalist hunters and almost any kind of spider will do. The Blue Mud Dauber, Chalybion californicum, is famous for killing black widow spiders, but it is also a generalist. It uses the old nests of the Black and Yellow Mud Dauber instead of building a nest from scratch.

Still other wasps don’t bother making a nest at all. The ichneumon Acrotaphus wiltii (above) simply locates a host (the orb weaver Neoscona arabesca in this case), stings it into brief paralysis, and lays a single egg on it. The wasp leaves, but her larval offspring will feed as an external parasite on the spider.

Flies are the quintessential victims of spiders, but some turn the table. Small-headed flies of the family Acroceridae, are parasites of spiders, especially trapdoor spiders.

The female fly lays hundreds or thousands of eggs, scattering them throughout the landscape. The larvae that hatch are highly mobile, host-seeking missles. Upon contacting a spider, the larva climbs up its host’s leg and burrows into the spider’s body wall. It takes up residence around the book lungs, feeding internally on its host.

A similar scenario is played out by members of the family Mantispidae, order Neuroptera. Females lay large numbers of eggs and the larvae emerge to go in search of spiders. Instead of eating the spider, they simply climb aboard and wait. What are they waiting for, you ask? A larva waits for a female spider to spin her egg sac, at which point it climbs inside and becomes wrapped up with the eggs. Then it eats the eggs, pupates, and eventually emerges as an adult mantispid. What if a larva climbs onto a male spider? It will transfer to a female during mating.

Among the most amazing spider predators are “helicopter damselflies” of the family Pseudostigmatidae.

These tropical giants hover in front of a spider web and simply pluck the owner off its silken platform. They are aquatic as nymphs, living in pools of water inside treeholes and preying on other small animals.

It should come as no surprise that perhaps the most lethal spider predators are…other spiders. Spiders may be able to negotiate their own webs, but can easily become entangled in another spider’s snare. Further, mating is risky business, even if you are not a black widow. Female spiders are usually larger and more powerful than their mates, and may eat potential suitors instead of courting them.

No spider hunter, however, matches the skill and stealth of the jumping spiders of the genus Portia, found in Africa, Asia, and Australia. They may build their own webs, unusual for jumping spiders, or actively stalk other kinds of spiders in their webs. Even other jumping spiders are a potential meal.

Have you ever seen a spider as the victim of another animal? Did it surprise you? Please feel free to share your stories here. I may also revisit this topic to address other spider-eating creatures.

Aknowledgements: Acrotaphus wiltii image by Tom Murray in Massachusetts and borrowed from Bugguide.net; Acrocerid fly image is of Eulonchus tristis, taken in Washington state by Stephen Hart and borrowed from Bugguide.net; Portia spider image taken from sgmacro, by Nicky Bay of Singapore; all other images by Eric R. Eaton unless otherwise noted.

Wasp Wednesday: Caliadurgus hyalinatus

The members of the wasp family Pompilidae are known as “spider wasps” because the adult females hunt spiders as food for their larval offspring. The elegant little species Caliadurgus hyalinatus is no exception. I found it to be quite common in Cincinnati, Ohio when I lived there and collected insects. It was like finding an old friend when my girlfriend Heidi Genter pointed out this specimen on goldenrod at Cape May Point State Park in New Jersey on October 18, 2010.

This wasp was formerly known as Calicurgus hyalinatus. Henry Townes, in his monograph Nearctic Wasps of the Subfamilies Pepsinae and Ceropalinae separated the species into four subspecies. Collectively, they range over most of the eastern U.S. and and adjacent Canada, west to Washington state, the Dakotas, and Kansas, south to Georgia and Louisiana with sparse records in Texas, New Mexico, and Arizona. This is also a holarctic species, found in Europe as well.

The famed French entomologist Jean Henri Fabre documented his observations of the species in Europe in More Hunting Wasp. Here in the U.S., Howard E. Evans and Frank E. Kurczewski have contributed to our understanding of this species in the New World. Information from their papers is presented in the following paragraphs.

C. hyalinatus apparently chooses only orb weavers of the family Araneidae to feed its offspring. Host records include the Starbellied Orb Weaver, Acanthepeira stellata, one of the furrow spiders, Larinoides patagiatus, the Humpbacked Orb Weaver, Eustala anastera, the Marbled Orb Weaver, Araneus marmoreus, and a species of Neoscona. The prey was an immature spider in every instance, not surprising given that this small spider wasp could not overpower mature orb weavers, many of which are quite large. The wasp must sting the spider into paralysis to facilitate its “cooperation” in being carted off by the wasp to the nest site.

The female wasp grasps her immobilized victim at the base of a leg, and then walks forward with the prey held in front of her. She may also climb a vertical object and fly (or at least glide) from it to achieve greater distance with more minimal effort. Once she arrives in a suitable spot she stashes the spider in a crotch in vegetation near the ground, and begins to excavate a burrow.

The wasp can work quickly in sandy soil, completing her simple burrow in about thirty minutes. She eventually surfaces, grabs her spider, and tows it underground. The tunnel is diagonal, about four centimeters in length, and terminates in a centimeter-long cell about four centimeters below the surface. The spider is left in the cell, on its “stomach,” with a single egg attached. The wasp then fill in the entrance to the burrow and begins the process anew.

Caliadurgus hyalinatus is not easily confused with any other spider wasp in North America. Females have clear wings with a dark spot on each front wing, a bicolored abdomen, and bicolored hind legs. The hind tibia has a noticeable row of teeth along the upper edge.

Sources: Evans, Howard E. and Carl M. Yoshimoto. 1962. “The Ecology and Nesting Behavior of the Pompilidae (Hymenoptera) of the Northeastern United States,” Miscellaneous Publications of the Entomological Society of America 3(3): 67-119.
Kurczewski, Frank E. and Edmund J. 1968. “Host Records for Some North American Pompilidae (Hymenoptera) With a Discussion of Factors in Prey Selection,” Journal of the Kansas Entomological Society 41: 1-33.

Spider Sunday: Tinus peregrinus

Nursery web spiders of the family Pisauridae are more diverse than I thought. I had been under the impression that there were only two genera in North America: Pisaurina and Dolomedes. Turns out there is another: Tinus. Thanks to Lynette Schimming at Bugguide.net, I found out that what I thought were immature fishing spiders I had observed in Tucson, Arizona and Mission, Texas were actually adults of Tinus peregrinus.

Whereas most adult fishing spiders and nursery web spiders are quite large (body length 10-28 mm), Tinus peregrinus maxes out at around 10 millimeters body length, males a millimeter shorter still.

This species ranges across the southwest U.S. from southern California to the southern tip of Nevada, and east to Texas and Missouri. It also occurs in northern Mexico. The “type locality,” the site where the first known specimen was collected, is listed as Hot Springs, Arkansas, but it is suspected that this is in error.

Virtually nothing is known of the life history and biology of this animal. Egg sacs in preserved collections are dated late July and early August. I have observed this species under bark on trees near the edges of ponds, and also at the edges of window frames. It would appear that once an individual spider finds a location that suits it, the spider stays put. One specimen I found in the corner of a window had several shed exoskeletons in its web, suggesting it had resided there for some time. No wonder, the web was also full of tiny midges (flies in the family Chironomidae) that had swarmed the lighted building at night.

Like most spiders in the Pisauridae, T. peregrinus appears to prefer the vertical plane, rarely found on the ground.

Sources: Carico, James E. 1976. “The Spider Genus Tinus (Pisauridae),” Psyche 83: 63-78
Kaston, B. J. 1978. How to Know the Spiders (Third Edition). Dubuque, Iowa: Wm. C. Brown Company Publishers. 272 pp.

Wasp Wednesday: Polistes flavus

One of the most conspicuous wasps in the Sonoran Desert is the paper wasp Polistes flavus. This is a large wasp that frequents the same narrow belt as saguaro cacti, seldom being encountered at lower or higher elevations. Its large size, and almost entirely bright yellow color helps to separate this species from every other paper wasp in the region.

Little is known about P. flavus despite its relative, if seemingly localized, abundance. I have seen nests on only a handful of occasions, and they were all placed under the eaves of buildings. Unfortunately, those observations were made before I started taking digital images. I do recall that the nests were large, if only because the paper cells needed to accommodate these wasps have to be correspondingly large. Fortunately, my good friend Margarethe Brummermann did manage an image or two, one of which is shown below.

You are most likely to see these wasps in one of three situations: at water, at flowers, and perching on prominent vegetation. Worker females often congregate around receding waters of the intermittent streams characteristic of the Sonoran Desert. They may even land on the water, sprawling across the surface film and drinking deeply. They will visit swimming pools when natural sources are not available. Many other species of desert Polistes and Mischocyttarus will exhibit the same behavior. They all need water to manufacture saliva to mix with wood fibers to create the paper used in building their nests.

Paper wasps attack caterpillars and other insects to take back to the nest to feed the growing larvae, but the adult wasps need carbs, not protein. Consequently, paper wasps make use of flower nectar and “honeydew” from aphid colonies. Look for Polistes flavus on the blossoms of Seep Willow (Baccharis salicifolia) and, to a lesser degree, Desert Broom (Baccharis sarothroides). The wasp in the image below is on a Seep Willow.

Male paper wasps are often even larger than the females and therefore even more obvious and intimidating. This is especially true when they engage in territorial behavior, perching on prominent twigs or branches along the edges of dry riverbeds and other flyways. From these outposts the males scan for passing females and rival males. They will also chase away other insects, then return to their perch or another perch close by. Males do not have stingers, but are powerful enough to back up their threats.

How do you tell a male paper wasp from a female? Males have longer antennae, dramatically hooked at the tip, and their faces are more “square” than those of females. Males tend to have very pale faces, too. Females have shorter antennae, not as prominently hooked, and triangular faces that are usually darker.

One paper wasp likely to be confused with P. flavus is P. apachus, which is colored in yellow and reddish brown. P. apachus almost invariably has two parallel yellow stripes on the top of the thorax (see below), whereas that area is almost entirely yellow in P. flavus. Another confusing species is P. aurifer, which is entirely reddish brown on top of the thorax.

Look for P. flavus in Arizona, as well as southern California, Nevada, Utah, New Mexico, and western Texas. Males can easily overwinter in milder parts of that range, though they are normally more common in autumn as colonies prepare to suspend activities for the colder months.

Spider Sunday: Bowl & Doily Spider

You don’t have to see a Bowl and Doily Spider, Frontinella communis, to recognize it immediately. The name says it all. Its web looks exactly like a bowl atop a “doily,” or saucer. It may be the most recognizable web outside of an orb web.

The Bowl and Doily spider is also one of the most common and widespread spiders in North America. The spider itself is not terribly impressive, mature females measuring only 3-4 millimeters in body length, and males slightly smaller. They are handsomely and boldly marked with black and white stripes on the abdomen, a brown cephalothorax, and brownish legs.

The webs are only a few inches across, and usually well off the ground, stretched between twigs, suspended from fences, and other objects. The spider hangs upside down on the bottom of the “bowl,” presumably awaiting prey to literally “drop in” for dinner. A tangled scaffold of silk lines suspends the bowl, and insects are likely to hit one of the threads and be caught by the upturned sheet below. At least one reference asserts that the spider pulls its prey through the bottom of the “bowl” and then retires to the “doily” to dine.

Another species in this genus, F. huachuca, is known from Arizona. I am wondering if the specimen I imaged in the Chiricahua Mountains at Onion Saddle (picture below) belongs to that species.

Bowl and Doily spiders are not only common, but locally abundant. Find one web and you will likely find dozens of others in close proximity. This may help facilitate mating. Males can be seen sharing the webs of females in late summer and fall.

Look for this species at forest edges and in pine woodlands especially, though it is just as likely to turn up in your yard, garden, or orchard. Note that earlier references treat the species as Frontinella pyramitela.

Wasp Wednesday: Not Wasp V

This is the fifth installment of “Wasp Wednesday” that treats another kind of insect often mistaken for a wasp. Today we entertain the clearwing moths of the family Sesiidae. Yes, some moths can pass for wasps!

My own experience suggests that sesiids are not terribly common. I have few in my collection and have not often observed them in the wild. Still, at least a few species are abundant enough to be considered pests, with much research devoted to their control, including the production of synthetic pheromones designed to trap adult moths. More on that later.

You are much more likely to see the moths than you are their larvae. The caterpillars of sesiids are borers, so are concealed in stems, roots, vines, or tree trunks for the entirety of their immature lives. You might be lucky enough to see where a caterpillar had been living because the molted pupa skin often protrudes from a hole where the moth exits.

They may be scarce, but clearwing moths are certainly diverse. There are over 1,100 species known (so far), in 120 genera. The narrow forewings, nearly devoid of scales except for the veins and wing margins, are characteristic. The front wings and hind wings connect in the manner of most moths, with a hook-like “frenulum” on the leading edge of the base of the hind wing interfacing with a patch of setae (hairs) on the underside of the forewing, called a “retinaculum.” However, there is also a unique series of scales on each wing that interlock with each other, further securing the wing coupling.

As you would expect, sesiid moths fly during the day, and one is most likely to find these mimics at flowers where they mingle seamlessly with their “models,” real wasps and bees.

I was fortunate enough to spy the orange-and-black specimen above as it flitted about an open field in Colorado Springs, Colorado on October 22, 2011. Euhagena nebraskae (no common English name, sorry) is one of those “clearwings” that actually does have an abundance of scales on the wings. The larvae of this species are known to bore in the roots of evening primrose (Oenothera spp.). It flies in the fall as an adult moth, and the species is known from southern Alberta to Mexico City, west to southern California. My friend Ted MacRae wrote a post on this species in his blog ”Beetles in the Bush”. My guess is that E. nebraskae mimics some kind of small spider wasp in the family Pompilidae.

I found another interesting sesiid back on August 1, 2009 in South Deerfield, Massachusetts. Contrary to its name, the Lesser Peachtree Borer, Synanthedon pictipes, feeds mostly under the bark of wild cherry. The caterpillars seem to prefer areas of the trees malformed from mechanical injuries, fungal infections, or other abnormalities. The adult moths are convincing mimics of a variety of wasps that share a black-and-white color pattern.

Pest species like the Lesser Peachtree Borer require monitoring in orchards where they can be problematic to census by simple observation. Consequently, during the 1970s, efforts were made to create synthetic pheromones (sex scents produced by the female moths to attract mates in this case). This strategy has paid off, and continues to do so. The only drawback has been the notorious persistence of the pheromones, even after washing and cleaning. Many an agricultural entomologist has been embarrassed in public by an entourage of eager male clearwing moths still sensing residual artificial pheromones on his or her person.

Despite the risk of ridicule, I am sorely tempted to purchase a variety of synthetic pheromones if it will result in more photo ops with these remarkable, beautiful insects. I would sure like to see another Glorious Squash Vine Borer, Melittia gloriosa, for example, like the one below from Pima Canyon in Arizona, August 29, 2010.

Sources: Covell, Charles V. Jr. 1984. A Field Guide to Moths of Eastern North America (Peterson Field Guide Series). Boston: Houghton Mifflin Company. 496 pp.
Powell, Jerry A. and Paul A. Opler. 2009. Moths of Western North America. Berkeley: University of California Press. 370 pp.
Moth Photographers Group
San Diego Natural History Museum
”Using Pheromones to Attract Clearwings”.

Spider Sunday: Spiders and Celebrities

Nobody has a neutral reaction to spiders, so it comes as no surprise that celebrities find themselves on one side of the fence or the other regarding their affection or disdain for the arachnid world.

Humorist David Sedaris has a fascination with the Giant House Spider, Tegenaria duellica. He wrote about them in the essay “April in Paris” in the book When You Are Engulfed in Flames. “April” is the name of one of the spiders that the author found inside his home in Normandy, France. He fed her flies and watched her behavior on his windowsill. He became so enamored that (in the essay at least) he took her to Paris to see the Eiffel Tower.

Actor Jim Parsons of The Big Bang Theory on CBS television pretended to be scared of spiders when he presented the word “arachnid” on an episode of Sesame Street. His real-life reaction is much more admirable: “….I’m not terribly afraid of them. I have a lot in my house, but I try not to kill them. I just shuffle them outside with a piece of paper.”

Dominic Monaghan of Lost fame is incredibly spider-friendly. He was set to join an expedition two or three years ago to re-discover an African tarantula, Hysterocrates hercules, known currently only from a museum specimen collected in Nigeria in the late 1890s (its description published in 1899). I had the pleasure of briefly meeting Mr. Monaghan at the annual “Bug Fair” in Los Angeles last May. He told me that the mission had yet to take place but that he was still optimistic that it would happen.

The spider-celebrity connection works the other way, too. Several recently-described species have been named after contemporary celebrities. Pachygnatha zappa immortalizes legendary rocker Frank Zappa. The species was collected on Mount Cameroon in Africa.

The North American trapdoor spider genus Aptostichus has species named after Angelina Jolie and Stephen Colbert. Jason Bond, the scientist and professor at East Carolina University who named these spiders also christened another trapdoor spider after Canadian musician Neil Young.

I hope that the celebrities feel honored to have arachnids bearing their namesakes. I know that I feel honored when I find arachnophiles anywhere, celebrities or not.