Wasp Wednesday: Clitemnestra bipunctata

Most species of insects are smaller than you would imagine. This is also true of wasps. For every species you notice, there are dozens you don’t. One common species that is easily overlooked is Clitemnestra bipunctata in the family Crabronidae.

At about 5-6 millimeters in body length, this wasp usually escapes notice. I have found them most commonly around aphid colonies where they lap up the aphids’ liquid waste, known as “honeydew.” The species ranges across most of the United States and is also recorded from Cuba.

When not living the luxurious lifestyle sipping sugary liquids, the female wasps hunt a variety of planthoppers, leafhoppers, treehoppers, and psyllids. The long list of recorded hosts (424 prey records from Cuba alone) includes Coelidia olitoria, Colladonus clitellarius, Japananus hyalinus (pictured below), Macrosteles fascifrons, Orientus ishidae, Paraphlepsius irroratus, and Prescottia lobata from the leafhopper family Cicadellidae.

Also found in excavated nests were the spittlebugs Clastoptera obtusus, Philaenus leucophthalmus, and P. lineatus; the treehopper Cyrtolobus acutus; and various members of the families Cixiidae, Dictyopharidae, Flatidae, Tropiduchidae, and Psyllidae. The wasps generally select adult hoppers much more often than nymphs.

Nests are burrows usually dug in bare soil near the top of vertical banks, and to a depth of 9-20 centimeters. One to three cells usually branch from the main tunnel. Each cell measures about six by ten millimeters, and the wasp stores 6-18 paralyzed prey per cell.

The satellite flies Phrosinella aurifacies and Metopia argyrocephala are reported as parasites of nests. The adult female flies enter the burrows and deposit live larvae inside. The larvae feed on the paralyzed prey, but often destroy the wasp egg or larvae as well. Adults of Climnestra bipunctata are preyed on by adults of the robber fly Diogmites angustipennis, and probably other predatory insects as well.

Note that this species was formerly known as Ochleroptera bipunctata, but that genus was merged with Clitemnestra by Bohart in 2000.

Sources: Evans, Howard E. and Kevin M. O’Neill. 2007. The Sand Wasps: Natural History and Behavior. Cambridge: Harvard University Press. 340 pp.
Evans, Howard E. 1968. The Comparative Ethology and Evolution of the Sand Wasps. Cambridge: Harvard University Press. 526 pp.
Bohart, R. M. and A. S. Menke. 1976. Sphecid Wasps of the World. Berkeley: University of California Press. 695 pp.

Spider Sunday: Gray Wall Jumper

Few arachnologists would argue that the most charismatic of spiders are the jumping spiders, family Salticidae. These agile hunters are about as “cute” as spiders can get. They have surprisingly acute vision, and will turn to look at you with one pair of enormous eyes when you approach them. Jumping spiders can also be very colorful. Few species are immediately recognizable, however, due to their great variability in color and pattern, and their generally small size. One species that is fairly identifiable is the Gray Wall Jumper, Menemerus bivittatus.

I was fortunate to encounter several pairs of this species living up to its common name on the exterior walls of the visitor center at Bentsen-Rio Grande Valley State Park in Mission, Texas in June, 2010. The Gray Wall Jumper is not native to North America, however, having been introduced from the Old World tropics. Here in the U.S. it is generally confined to Florida, Texas, and southern California.

Jumping spiders, and hunting spiders in general, differ from web-building spiders in that both genders are nearly identical in size. Female Gray Wall Jumpers (image above) are 8-10 millimeters in body length at maturity, whereas males (images at top and below) are 8-9 millimeters. The striking differences are in their color pattern. The male has more or less a reverse color pattern from the female, at least on the abdomen. I initially thought I had taken images of two different species.

A flat, vertical surface seems an odd “habitat” for any organism, but Menemerus makes the most of it. The spiders actively stalk small flies that bask in such situations, or that are attracted to lights at night. They are strong enough to bring down fairly large crane flies, and subdue something the size of a house fly, too.

One can’t help but become enamored with these spiders, especially after seeing them in action. This video gives you just a glimpse of their behavior. See if you can identify the males and females in that clip.

The female spider constructs a lens-shaped egg sac to hold 25-40 eggs. She guards the sac inside a silken retreat that is about 1.5 centimeters in diameter. She’ll also protect the spiderlings after they emerge, for a total of roughly three weeks from egg-laying to dispersal of her offspring.

In places where their respective ranges overlap (Texas), the Gray Wall Jumper may be mistaken for the species Platycryptus undatus, shown below, or vice versa. Both are likely to be encountered on vertical surfaces such as outside walls, and they are very similar in size and markings. Platycryptus is native, however, and has a much more extensive range, extending far to the north into southern Canada.

Be sure to look for the Gray Wall Jumping Spider in your travels abroad, too. It is essentially cosmopolitan in tropical and subtropical regions throughout the world, including Japan, India, Thailand, Paraguay, and even the Galapagos Islands.

Sources: G. B. Edwards, Jr. 2002. Featured Creatures: Jumping Spiders, University of Florida (Gainesville).
Arachne.org.au

Wasp Wednesday: Recent Mentors

I suppose that “recent” is a relative term, but I am delighted to report that the following gentlemen are all still alive and continuing to make very valuable contributions to science. They inspire me and make me a better entomologist and writer.

Arnold Menke, Eric Grissell, myself, Justin Schmidt

I was privileged to have the opportunity to work on a private contract to help curate the national butterfly collection at the National Museum of Natural History (Smithsonian) in April and May of 1986, where I got to meet two fine scholars working there on behalf of the USDA’s Agricultural Research Service. Dr. Arnold Menke is a world authority on wasps, especially the thread-waisted wasps in the genus Ammophila. He currently has nearly all my specimens of that genus, in fact, as he is working on a much-needed revision of those caterpillar hunters. He retired to Bisbee, Arizona in the 1990s where he also enjoys railroad history and photography.

Dr. Edward Eric Grissell (he goes by “Eric,” too, which can cause confusion at Arnold’s annual hamburger roast) is an expert on tiny parasitic wasps in the suborder Chalcidoidea. Since many of those wasps are enemies of agricultural pests, Eric was a very busy man figuring out which species could help control food-destroying insects. Today, Eric is also “retired,” but writes full-time about insects and gardening. He has produced several outstanding popular books including Thyme on my Hands, Insects and Gardens: in Pursuit of a Garden Ecology, and Bees, Wasps, and Ants: The Indispensable Role of Hymenoptera in Gardens, all published by Timber Press.

Another remarkable individual is Justin Schmidt, known famously as the “King of Sting” for his exploits in assessing the effects of insect and arachnid venoms on willing human subjects, but mostly himself. He created the “Schmidt Sting Pain Index” to quantify and describe (in prose usually reserved for connoisseurs of wine) the type of pain inflicted by stinging insects. He worked for many years at the federal Carl Hayden Bee Research Center in Tucson, before deciding to pursue his own projects full time. I greatly admire his endless curiosity, and ability to devise experiments to divine answers to his questions.

Matthias Buck

Last, but certainly not least, is Dr. Matthias Buck, currently the Assistant Curator of Invertebrate Zoology at the Royal Alberta Museum in Edmonton. I first met him online as I recall, since he freely shares his expertise on Bugguide.net. Eventually we met in person at a meeting of the Entomological Collections Network. His specialty is vespid wasps, which includes the yellowjackets, hornets, paper wasps, mason wasps and potter wasps. One of his most amazing projects is the co-creation of the Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the Northeastern Nearctic Region, along with Stephen A. Marshall and David K. B. Cheung. Matthias has all my Polistes paper wasps, and has already found examples of an undescribed species among them.

I can honestly say that it is an honor to know these men both as scientists and human beings. I will be forever grateful to them for sharing their knowledge and encouraging me along the path that I have chosen.

Spider Sunday: Thieves and Hangers-on

Not all enemies of spiders kill them. Some will steal a meal. Others aren’t really enemies, but escape their own enemies by hiding out on spider webs.

While in Massachusetts, I was lucky enough to witness a common scorpionfly, Panorpa acuta, scavenging prey in the web of a sheetweb-weaver (family Linyphiidae). The spider tried to chase off the pesky mecopteran, as evidenced by the image below.

Common scorpionflies are in the family Panorpidae, order Mecoptera. They are named for the enlarged claspers of the male, part of his external genitalia. They are so large that the male must curl the end of his abdomen, giving him the appearance of a scorpion. The “long face,” terminating in chewing mandibles, also helps to identify these insects.

They go through complete metamorphosis, the larvae living in soil and leaf litter on the forest floor where they also scavenge on dead or dying, soft-bodied insects. They go through four instars (the intervals between molts), before pupating in an earthen chamber in the soil.

Another phenomenon I saw in Massachusetts was the use of spider webs as roosting places for a certain species of gall midge, family Cecidomyiidae. Gall midges are a type of fly. Whereas most flies become tangled in spider webs and eventually a meal for the spider, these tiny flies are able to select the non-sticky foundation threads of spider webs and safely suspend themselves from them. Predators of the flies, if they even managed to notice them, would risk becoming tangled in the spider web should they attempt to catch one of the diminutive midges.

This trapeze act is apparently a widespread phenomenon in the Cecidomyiidae, especially in the subfamilies Porricondylinae and Cecidomyiinae. The behavior was first reported (published) in 1853 by Johannes Winnertz.

Sources: Byers, George W. 2002. “Scorpionflies, Hangingflies, and Other Mecoptera,” Kansas School Naturalist. 48(1): 1-15.
Gagne, Raymond J. 1989. ”Family Cecidomyiidae” in Catalog of the Diptera of Australasia and Oceania, Neal L. Evenhuis, editor. Honolulu, HI: Bishop Museum & E. J. Brill. 1155 pp..