Pantropical Jumping Spider

This week, if you live pretty much anywhere north of Mexico, a tropical vacation sounds pretty appealing. Well, if you were a Pantropical Jumping Spider, Plexippus paykulli, you would probably be enjoying yourself right now. This species is a world traveler, now dispersed to most tropical and subtropical climates across the globe. Envious?

Male

The Pantropical Jumper is pretty easy to find, too, since it hangs out on the exterior of buildings where it can be quite conspicuous. The only problem might be telling it apart from the Gray Wall Jumper which is often seen on buildings, too. Both species are of similar size. Adult females of the Pantropical Jumper are 10-12 millimeters in body length; males average 9.5 millimeters.

Female

Plexippus paykulli is also sexually dimorphic, meaning that the male gender looks radically different from the female sex. In fact, it would be easy to assume they are two different species. This is typical of many jumping spiders: the males are adorned with colorful scales, or tufts of hair on their legs and/or pedipalps which are used to communicate with the female through elaborate displays, often accompanied by vibrations carried through the substrate (surface on which the spiders are sitting).

Male

Pantropical jumpers don’t sit on the beach sipping fruity drinks. Nope. They actively seek prey by day, including small moths, flies, flying ants, and even other spiders. They have the typical behavior of most jumping spiders in the family Salticidae, running a short distance, pausing, pumping their pedipalps up and down, and turning to face whatever piques their curiosity (or perceived threat).

Mated females of this species spin a small, flat egg sac about nine millimeters in diameter that contains anywhere from 35-60 eggs. A larger silken envelope, 25-35 millimeters around, covers the egg case and serves as a retreat for the female to guard her future offspring. Look for these nurseries under eaves of buildings, in cracks and crevices, or under boards and other objects.

Female

Here in the United States, Plexippus paykulli can be found year-round in South Carolina, Georgia, Florida, the Gulf Coast states, and south Texas. Outlying populations in New Mexico, and north along the Atlantic seaboard are probably the result of accidental introductions. You are also likely to see this spider in such exotic locales as Hawaii, Hong Kong, India, Greece, and parts of Africa. It is assumed that the species is native to southeast Asia.

The Pantropical Jumping Spider should be considered an asset to any resort, hotel, or motel, for they are literally a mobile pest control service. They are known to hunt mosquitoes and small cockroaches among other pests. I guess you would call that a “working vacation.”

Male

Sources: Bradley, Richard A. 2013. Common Spiders of North America. Berkeley: University of California Press. 271 pp.Edwards, G.B., Jr. 2002. “Jumping Spiders,” Featured Creatures. Division of Plant Industry and University of Florida.
Gaddy, L.L. 2009. Spiders of the Carolinas. Duluth, MN: Kollath+Stensaas Publishing. 208 pp.
”Pantropical Jumper,” iNaturalist.

Fly Day Friday: Snow Flies

As I write this, the outdoor temperature here in Colorado Springs is a whopping 5° F. There are going to be few, if any insects out and about in those frigid conditions. A sunny winter day, even higher up in the mountains, could provide a different story. There are wingless crane flies that can be seen crawling across the snow in the dead of winter.

Last October 27, 2012, I was fortunate enough to take a trip with other members of the Aiken Audubon Society to Guanella Pass (Clear Creek County) in search of ptarmigans. We got skunked on the birds, but one person in our party spotted a tiny insect creeping across the snow. I instantly recognized it as a wingless crane fly, though I had only seen images of them until then.

There are sixteen species of “snow flies” in the genus Chionea in North America. They are in the crane fly family Limoniidae, formerly a subfamily of the Tipulidae. While western species are mostly confined to mountain ranges, eastern species can be found in most forested areas, especially in regions that experienced glaciations during the most recent ice age. They appear most commonly in October and November, and again in February and March.

While these dark flies are most conspicuous on the surface of the snow, most of the time they are concealed in the tunnels of small mammals, beneath leaf litter, or fairly deep in caves. These situations help to insulate them from truly severe weather, and an adult snow fly may live up to two months.

Drawing by Dr. George Byers

The life cycle of Chionea remains mostly a mystery. Every attempt to rear them in the laboratory has failed because no one knows what the larval stage feeds upon. We do know that an adult female fly can produce up to 194 eggs, each one laid singly. Lacking wings, the female fly can store eggs even in the thoracic cavity that is normally packed with wing muscles.

Eggs take eight days to three weeks to hatch under laboratory conditions. Larvae have fairly hardened mouthparts, suggesting they may be able to take in solid food. Just what that nourishment could be is up for conjecture. Maggots of distantly-related flies feed on fungi that grow on bat guano in caves, but that information may or may not be relevant to snow fly larvae. We do know the larvae feed and grow during the summer months, with pupation taking place in the fall.

Adult snow flies have few enemies, but we know that mice are among their predators. Believe it or not, this conclusion is reached from knowledge of the cycle of parasitic tapeworms. Rodent tapeworm eggs expelled in the feces of a mammal must be consumed by an insect, usually a larva. Once inside the insect, the tapeworm metamorphoses into a “cysticeroid” stage. There it remains until the insect is in turn consumed by a rodent. Tapeworm eggs have been found in the gut of adult snow flies.

Rock-crawlers, primitive insects related to mantids and cockroaches, are also predators of snow flies. Grylloblattids, as rock-crawlers are known in the scientific community, are found in isolated populations at high elevations in western North America.

How do snow flies keep from freezing to death? First, snow flies occupy the “subnivean” environment: a microclimate that exists in cavities beneath the snow created by arching grassblades, leaf litter, and rodent tunnels. These nooks and crannies offer protected niches with temperatures that are milder than the surface and air temperatures above.

Snow flies also have a body chemistry to cope with the cold. Many insects have glycerol in their body fluids, which acts as an antifreeze, preventing the formation of sharp, life-threatening crystals of ice inside the insect’s tissues. Differing enzyme systems also allow snow flies to function at lower temperatures than most insects. In fact, they are susceptible to overheating!

The temperature in the room where I write this is not that warm, either. I am not believing the 66° registered on the digital thermometer and, lacking my own internal antifreeze, will go open a can of soup. Stay cozy, friends.

Source: Schrock, John R. 1992. “Snow Flies,” Kansas School Naturalist 38(2): 1-16.

Ichneumon Wasp: Ceratogastra ornata

Welcome to "Wasp Wednesday." The wasp family Ichneumonidae is one of the most diverse in the order Hymenoptera, especially in the largely temperate climate of North America. Many species look superficially alike, even if they belong to different genera. One of the few species I can usually identify in the field is Ceratogastra ornata, which I still often mistake for a spider wasp anyway.

This wasp is well-named, for it is ornately patterned with yellow and reddish brown or black, depending on the geographic location where one finds them. In fact, four subspecies are recognized. Collectively, they are distributed from southern Ontario, Massachusetts, and southern Wisconsin west to eastern California and south to northern Florida, Louisiana, and Mexico.

Specimens from the northern reaches of the species’ range are generally darker, including the wings, with reduced yellow markings. Specimens from farther south and west, like the one shown here from Colorado Springs, are distinctly paler.

It has been suggested that this wasp is a mimic of stinging spider wasps in the genus Poecilopompilus. Indeed, the similarities in color and pattern are striking, though the spider wasps are slightly larger than the ichneumon's 10-12 millimeter body length in most cases. Here in Colorado Springs, I found another spider wasp, Ceropales, to be a potential model for the ichneumon.

Ceropales sp.

How do you tell the ichneumon wasp from the spider wasp it mimics? Look at the antennae for one clue. Ichneumon wasps have many, short antennal segments while spider wasps have far fewer, and longer, segments. Wing venation offers other characters, but one seldom gets a good look. Images of ichneumons may capture the “horse head” cell near the middle of the front wing, the horse’s “nose” pointed toward the wingtip.

Look for Ceratogastra ornata visiting flowers, especially composites. They are not only seeking nectar, but hosts for their larval offspring as well. You might see a wasp that appears to be stinging a flower bud, but this behavior is aimed at the eggs of a moth instead.

Details are sketchy, but apparently females of some moths in the genus Feltia (family Noctuidae, the owlet moths) lay their eggs in certain flowers. The caterpillars that hatch then migrate to the ground where they finish their life cycle as subterranean “cutworms.” The ichneumon wasp intercepts the egg stage, or newly-hatched caterpillar, injecting her own egg into the host. Her larva lives as an internal parasite of the caterpillar, likely letting it mature before feeding in earnest and ultimately dooming its host.

I have personally witnessed female Ceratogastra ornata ovipositing in buds of Common Ragweed, Ambrosia artemisiifolia. The entomologist J.C. Bridwell has also observed this, and found them ovipositing in Eupatorium thoroughworts as well. The wasps also visit goldenrod flowers, but are not known to oviposit among the blossoms (Carlson, 2009). The specimen shown here was favoring the extrafloral nectaries of Common Sunflower, Helianthus anuus.

The inability to identify ichneumon wasps to species should not be a barrier to observing them, or even collecting them. We know precious little about the biology and geographic range of the majority of species. Your images, posted to Bugguide.net, could shed light on this interesting group. Bob Carlson, a world authority on Ichneumonidae, often offers his expertise there as well.

Sources: Carlson, Robert W. 2009. “Database of Hymenoptera in America North of Mexico,” Discover Life
Eaton, Eric R., et al. 2011. “Species Ceratogastra ornata,” Bugguide.

Post 400

Dendroctonus sp., © Eric R. Eaton

I can hardly believe I have reached this milestone of a 400th post on this blog. When I started way back in February of 2009, I faced many unknowns. Would I have the discipline to write regularly? Would anyone read the posts? Back then, I knew nothing of social media, and hadn’t even started taking my own images.

There have been many life changes along the way, too. I became unemployed, employed irregularly and temporarily, and am now unemployed again. I met a wonderful woman, moved to her city, got married, and combined households. I have traveled fairly extensively, accruing images as I go.

My major goal in creating a blog was to help educate the general public about insects, arachnids, and other arthropods. I am still unsure if I am only “preaching to the choir,” but Facebook (and now Twitter) have helped extend the reach of this blog. As of yesterday, I was ranked number seven for invertebrate blogs on the Nature Blog Network (and #83 for all blog subjects).

What of the future of this blog? Expect it to continue. Do not expect me to move to WordPress. I find the interface to be horrible for me as a writer. I know this means you cannot easily view the blog on mobile devices; I know some complain that they cannot post comments. My apologies for that, but these are problems with Blogger, not me. Why they are not more responsive is beyond my comprehension.

You can expect more, and more frequent, content during the winter months when I am traveling less and spending less time in the field. You can always make requests for blog topics. I will gladly research and write about the subject you wish to know about, provided I have images, or you have some you can share to illustrate the topic.

“Spider Sunday,” “Moth Monday,” “True Bug Tuesday,” “Wasp Wednesday,” “OrThoptera Thursday,” and “Fly Day Friday” will continue to be irregular features, with a total of roughly two or three blog posts made each week. Whenever possible, I want to include images of the immature stages, especially for moths, but I have few identified caterpillar images of my own at present, perhaps even fewer that correspond to my images of moths.

So, this blog will continue, but is subject to change depending on what you, the audience, wants out of it. I welcome your suggestions, criticisms, and complaints, as always. Feel free to e-mail me if you cannot comment directly. Thank you. BugEric24ATyahooDOTcom.