Tuesday, September 30, 2014

Field Guide, Anyone?

The Christmas shopping season is fast approaching, and I would like to make your gift-giving decisions easier by offering signed copies of the Kaufman Field Guide to Insects of North America to you, my loyal followers, for a discount.

I am happy to write a personalized message in the book and send it to you for $16.00 U.S., plus shipping. This is a savings of nearly three dollars off the cover price of $18.95. Please place your requests by October 15 to insure ample time for me to order additional copies from the publisher, and ship the book(s) to you in time for you to deliver it to your family members, friends, students, yourselves, or other loved-ones for the holidays.

Please e-mail me with "Field Guide Order" in the subject line: BugEric24ATyahooDOTcom. I will keep you appraised of the timeline for receipt of the book(s) so you can know when to expect delivery. I can accept only checks for payment, please.

As always, I also greatly appreciate donations to keep this blog running; and I always welcome your requests for topics and other improvements to this site. Thank you!

Thursday, September 18, 2014

Blue-winged Grasshopper

The band-winged grasshoppers in the subfamily Oedipodinae (family Acrididae) are easy to love. They are colorful and noisy in flight, seldom qualify as pests of agriculture or rangeland, and are endlessly diverse. A case in point is the beautiful Blue-winged Grasshopper, Trimerotropis cyaneipennis.

I first became acquainted with this species during childhood trips to eastern Oregon. They were fairly plentiful around Fort Rock in northern Lake County, but a real challenge to catch, even with a net. Nothing has changed, it took me several tries to net one that Heidi and I encountered in Water Canyon in the Magdalena Mountains of New Mexico last Sunday. I wanted to show Heidi, and my readers here, the blue-green hind wings that give this species its common name.

Like all members of the genus Trimerotrois, T. cyaneipennis is incredibly cryptic when at rest among rocks, or on bare soil. The front wings, called tegmina (singular is "tegmen"), are narrow and in this case speckled with brown, gray, and black, creating vague bands. The hind wings are used in flight, and fold like a Japanese fan, accordion-like, when not in use, concealed beneath the tegmina.

Even if you can follow the flight path of one of these insects, and note where it lands again, good luck spotting it unless it moves. Actually, it might even walk a short distance once it does land, making it even more maddening to locate.

The cloak of (near) invisibility works well, despite the fact that these are not small creatures. Adult males measure 25-35 millimeters, females 28-40 millimeters. Besides the blue hind wings, they can be identified in part by the bright blue tibia ("shin") segment of the hind leg, and the blue tint on the abdomen, visible in the image below.

This grasshopper is most common in rugged, mountainous terrain and canyons at elevations between 3,000 and, 8,500 feet. Look for them along gravel roads, and volcanic soils, especially at the base of steep slopes. They tend to favor oak, pinyon-juniper, or pine forests west of the Rocky Mountains from southeast Washington, Idaho, eastern Oregon, California, Nevada, Utah, southwest Colorado, Arizona, western New Mexico and extreme west Texas. They also range just across the Mexican border.

You might hear this grasshopper when it takes flight, as it generates a loud crackling sound as the veins of the hind wing rubs against the underneath surface of the tegmen. This is called "crepitation," and can be initiated at will by the insect, such that it can also fly silently.

There is continuing debate over the exact status of this species, and in southeast Wyoming, central Colorado, and much of eastern New Mexico, it is replaced by the closely-related "Brother's Band-winged Grasshopper," Trimerotropis fratercula. That species has yellow, or greenish-yellow hind wings, but even T. cyaneipennis does not always have obviously blue or turquoise wings.

Since this is more or less a "wilderness" grasshopper that does not eat crops or rangeland forage, it is not considered a pest. All the more reason to enjoy an encounter with this blue-winged beauty.

Sources: Bentley, Tom and David Ferguson. 2007. "Species Trimerotropis cyaneipennis - Blue-winged Grasshopper," Bugguide.net.
Capinera, John L., Ralph D. Scott, and Thomas J. Walker. 2004. Field Guide to Grasshoppers, Katydids, and Crickets of the United States. Ithaca: Comstock Publishing Associates (Cornell University Press). 249 pp.
Helfer, Jacques R. 1972. How to Know the Grasshoppers, Cockroaches and Their Allies (2nd Ed.). Dubuque, Iowa: Wm. C. Brown Company Publishers. 359 pp.

Tuesday, September 16, 2014

Hackberry Psyllids: A Fixture of Fall

Sometimes, it is easier to identify an insect by the evidence it creates than by seeing the bug itself. Such is the case with the abundant, but tiny, hackberry psyllids, genus Pachypsylla in the family Psyllidae and true bug order Hemiptera. Psyllids are also known as "jumping plant lice" for their resemblance to aphids and ability to vault themselves away from danger.

Along one of the streets that borders our townhouse complex in Colorado Springs are a pair of hackberry trees, among the few planted ornamentals that are not oak, maple, or elm. They are invariably exploited every summer by Pachypsylla celtidismama, which produces "nipple galls" on the underside of hackberry leaves. The small, tumor-like growths do not seem to affect the health of the tree in the least, but provide housing and food for the tiny insect within each one. Up to 52 galls have been found on a single leaf (Caldwell, 1938), and they vary from smooth in texture to rather hairy. Double and triple galls are not unheard of, but it is rare to find more than one nymph occupying each gall.

The adult stage of hackberry psyllids will start appearing shortly, if they are not emerging already. Adults of P. celtidismama are only 3.5-4.5 millimeters in length from "nose" to the tips of the folded wings. They resemble tiny cicadas, but can also be confused with barklice, order Psocodea. Barklice have chewing mouthparts, though, while psyllids in general have beak-like piercing-sucking mouthparts they use to tap plant sap.

Hackberry psyllids make themselves a real nuisance when they start seeking nooks and crannies in which to hibernate. They can gather by the dozens, if not hundreds, on the exterior of doors, window screens, and the siding of homes. They pose no threat, of course, and simply hosing down the masses with water will solve the problem. The appearance of these insects en masse is a brief affair anyway.

A different Pachypsylla species

Next spring, female psyllids will deposit eggs on the leaves of hackberries at the precise time when the leaves begin unfolding from the bud. Should a psyllid deposit her eggs too early, or too late, and the chances of successful development of her offspring plunges dramatically.

The formation of the bulging gall is the tree's response to the feeding of the nymph that hatches from the egg. The little dome-like pocket insulates the nymph from hostile abiotic environmental factors, and protects it from at least some predators and parasites. The nymph goes through five stages, the last instar illustrated in the images below. Note the two pairs of developing wing pads. The spike-like projections on the rear of the insect will help it to cut an exit in the gall before it emerges as an adult.

Nymph of P. celtidismama © Hannah Nendick-Mason via Bugguide.net
Nymph of P. celtidismama © Hannah Nendick-Mason via Bugguide.net

Despite their seemingly impenetrable fortress, the nymphs are still vulnerable to tiny parasitic wasps, including Psyllaephagus spp. (family Encyrtidae), and Torymus spp. (family Torymidae). The larval wasps feed as parasites on the nymphs and then chew their way out of the gall once they complete development.

Psyllaephagus sp. © John Rosenfeld via Bugguide.net

This, and the other six species of hackberry psyllids, range pretty much wherever hackberry occurs naturally, and increasingly where it is used as an ornamental tree. The different species of psyllids make correspondingly different styles of galls, so it is easiest to assess the gall shape, size, and location to determine which psyllid is responsible. Keep in mind that gall midges (family Cecidomyiidae) can also create galls on hackberry.

You might try rearing a few galls to see what parasites emerge along with the adult psyllids. It is entirely possible you could record a new host record in the process.

Sources: Berenbaum, May R. 1989. Ninety-nine Gnats, Nits, and Nibblers. Urbana: University of Illinois Press. 263 pp.
Caldwell, John S. 1938. "The Jumping Plant-lice of Ohio," Ohio Biological Survey Bulletin 34, vol. VI, No. 5: 229-281.
Winterringer, Glen S. 1961. "Some Plant Galls of Illilnois," Story of Illinois Series No. 12. Urbana: Illinois State Museum. 51 pp.

Sunday, September 14, 2014

A Jumping Spider, Tutelina similis

When my wife and I were in Atlanta back in June of this year, I had the opportunity to walk from our downtown hotel out to the Fernbank Natural History Museum along a route prescribed by one of the Google services. Taking a detour into a wooded ravine along a creek led to the discovery of a lovely little jumping spider, Tutelina similis.

Since signing a contract to do a new field guide to U.S. spiders for Princeton University Press, I have been crafting a species list. Upon first spotting a male T. similis I thought to myself: "That is not on my list. It sure is now!" I had no idea at the time exactly what it was, other than a member of the Salticidae, but its bold, attractive markings made it stand out.

What are we looking at when we stare into the face of one of these? Well, the pedipalps are the most obvious feature. Those are the short, leg-like mouthparts. In this case, they are black on the outer half, with a fringe of long white hairs on the inner half. The palps usually hide the chelicerae (jaws) unless the spider drops the palps and raises its "head" (cephalothorax). This species also appears to have "eyebrows" in the form of short black lines on the cephalothorax immediately behind the very large anterior median pair of eyes. It makes the spider appear to be in a state of perpetual surprise (or anger, depending on your viewing angle).

Despite their small size (4.0-5.0 millimeters body length), these are pretty conspicuous spiders that in this case were prowling understory vegetation about three to four feet off the ground. The sunlit patches where the deciduous tree canopy opened up seemed to be a favorite hunting ground. Indeed, insect activity peaks in these situations where flies, wasps, bees, and other potential prey bask, and defend territories.

Browsing through Bugguide.net, I was able to identify this species. My friend Troy Bartlett had even photographed a few. The overwhelming number of records on that website are from the month of June, so apparently the spiders mature at that time.

Like most jumping spiders, this species exhibits sexual dimorphism. That means that mature males differ markedly in appearance from mature females. I did not find any females myself, but below is an example of one from Hastings, Ontario, Canada, via Bugguide.net. The females are slightly larger than the males, but not dramatically so.

© Jason King

Tutelina similis is transcontinental in its Canadian distribution, and ranges east of the Rocky Mountains in the U.S. to at least Georgia and New Mexico. It has been found on mailboxes in rural Massachusetts (Edwards & Edwards, 1997), and in the seedheads of pitcher plants in Maine (Jennings, et al., 2008).

At least one population of this species in Utah was found to be a specialist predator on ants, even mimicking ants in color and behavior as it prowled over sagebrush. The front legs of these arachnids are waved about in the manner of ants waving their antennae (Wing, 1983).

It is species like this that make jumping spiders a favorite among people who study spiders. The wide-eyed stare and curious nature of salticids is enough to melt the heart of the most extreme arachnophobe, and endear them to gardeners and homeowners who might level a shoe at any other arachnid. Couple that with the extraordinary hunting skills that make jumpers heroes in the war on pests, and you have pretty much the poster child for why we should embrace spiders as a whole.

Sources: Edwards, Robert L. and Eric H. 1997. "Behavior and Niche Selection by Mailbox Spiders," J. Arachnol. 25: 20-30.
Jennings, Daniel T., Bruce Cutler, and Bruce Connery. 2008. "Spiders (Arachnida: Araneae) Associated with Seed Heads of Sarracenia purpurea (Sarraceniaceae) at Acadia National Park, Maine," Northeastern Naturalist 15(4): 523-540.
Richman, David B., Bruce Cutler, and David E. Hill. 2012. "Salticidae of North America, Including Mexico," Peckhamia 95.3: 1-88.
Wing, K. 1983. "Tutelina similis (Araneae: Salticidae): An Ant Mimic That Feeds on Ants," J. Kans. Entomol. Soc. 56(1): 55-58.