Thursday, July 31, 2014

Thistle Grasshopper

Grasshopper populations in general tend to fluctuate greatly over time depending on whether a given year is "wet" or "dry." Some species prosper more during dry years, while others are more abundant in wet years. This spring and summer has been decisively wet here on the Front Range of Colorado, with a corresponding explosion of species like the Thistle Grasshopper, Aeoloplides turnbulli, the subject of this week's "OrThoptera Thursday."

Initially, I mistook this species as "just another Melanoplus species," and indeed it belongs to the same subfamily (Melanoplinae) of the family Acrididae (short-horned grasshoppers). The Melanoplinae are collectively known as spur-throated grasshoppers for the peg-like process jutting from beneath their "neck." It is not an obvious feature unless you grab a specimen and turn it over.

The Thistle Grasshopper is of average size for acridids, males measuring 16-20 millimeters, and females 19-25 millimeters. It varies from greenish to mottled gray or brown, with yellow antennae and bold stripes behind the eyes. The hind femora ("thighs") are strongly banded; and the hind tibiae are blue. Wing length varies, at least by subspecies. The northern subspecies, A. t. turnbulli tends to have the wings shorter than the length of the abdomen by 2-4 millimeters. The southern subspecies, A. t. bruneri, has wings that exceed the length of the abdomen.

The name "Thistle Grasshopper" is a bit of a misnomer. They are not associated with true thistles (Cirsium spp.), but are found where Russian Thistle, better known as "tumbleweed," has taken over the landscape. A. turnbulli feeds on a variety of other plants as well, especially saltbush (Atriplex spp.), which is native and exceedingly abundant in the shortgrass prairies abutting the Rocky Mountains.

The Thistle Grasshopper ranges from Alberta and Saskatchewan south through Montana, Wyoming, Colorado, New Mexico, the Dakotas, Nebraska, Kansas, northern Oklahoma, and western Texas. It is apparently expanding its range eastward, so keep an eye out for it in adjacent states. The adults are present between June and October.

Pair in copula, male on top

If this species stuck to eating tumbleweeds and other invasive plants, it would be considered a highly beneficial insect. Unfortunately, its diet also includes sugar beets, and it has historically been a pest of that crop. A. turnbulli also competes with livestock on occasion, eating forage plants like lambsquarters, winterfat, kochia, saltbush, and other members of the family Chenopodiaceae.

Given the extreme proliferation of Russian Thistle here on the edge of the plains, I am still inclined to be a fan of the Thistle Grasshopper. We had the "tumbleweed apocalypse" around here last year, with various government agencies, homeowners, and ranchers struggling over ways to unclog roadways and fencelines, and uncover houses and vehicles every time we had strong winds. Go Aeoloplides turnbulli!

Sources: Capinera, John, L., Ralph D. Scott, and Thomas J. Walker. 2004. Field Guide to Grasshoppers, Katydids, and Crickets of the United States. Ithaca, New York: Comstock Publishing Associates (Cornell University Press). 249 pp.
Pfadt, Robert E. 1996. "Russianthistle Grasshopper," Wyoming Agricultural Experiment Station Bulletin 912

Wednesday, July 30, 2014

"Bug Eric" on Social Media

Are you active on Facebook? Twitter? If so, you might find it easier to connect with me there during the spring, summer, and fall when I am more apt to be out in the field instead of blogging. Here are links to some of my social media pages.

While I do have a private Facebook page where you can "friend" me, I post links, images, and other things entomological to my professional page here. Look for this banner image ("cover photo"), though it changes every so often.

I also started a group page on Facebook called "Arthropods Colorado". That is usually where I will first post recent images that I have taken in the field. This is also a growing community with many other wonderful people posting their images and observations of Colorado insects and arachnids. The Green Fool Grasshopper is our unofficial mascot, adorning the cover photo for the group page. Just ask to be added to the group and I will do so.

I also have a Twitter account, but rarely "tweet," so while you can follow me here, you are unlikely to get too much more than notifications of new blog posts. The banner image for my Twitter page is a pair of beewolves.

Increasingly, my LinkedIn profile is getting more looks, and it is where I update my professional activities. You can view my work history and ask to connect with me here. You will see this mug shot if you are in the right place.

Another place I frequent is perhaps not what you would call a social media website, but a page where people from all over the world post their images of fauna and flora. My account at Project Noah includes "spottings" from Colorado as well as other places where Heidi and I travel to. Yes, the majority of posts are insects or other arthropods, but I also throw in a few birds, mammals, herps (reptiles and amphibians), and wildflowers, too. Please consider joining Project Noah, as many of its "missions" as you care to, and post your own images. Once there, you can "follow" me and I can follow you.

Lastly, while I am not fond of the changes in their format, I still have a Flickr.com account here. I try and post fairly regularly, especially after a trip out of state.

I look forward to seeing you on one or more of the media platforms above; and I thank you for your patience between blog posts. Once summer ends, posts should be more frequent, and the diversity of topics will broaden as well.

Thursday, July 24, 2014

Blue-legged Grasshopper

This spring, Colorado Springs received consistent precipitation for the first time in several years. The rains resulted in lush plant growth and a corresponding explosion of grasshopper abundance and diversity. Some species I have not seen before, including the subject of this week's "OrThoptera Thursday," the Blue-legged Grasshopper (Metator pardalinus).

This beautiful animal is hard to mistake for any other grasshopper. The streamlined body is "leopard-spotted," a pattern common to many other species, but the hind femur is proportionately longer and more slender than in other band-winged grasshoppers. The inside of the hind femur, and the hind tibia, are bright blue. The abdomen can also have a flush of blue. The hind wings, exposed in flight, are bright red, pinkish, orange, or yellow, with a bold black band beyond (see image below). Adult males measure 26-38 millimeters while females are 32-45 millimeters.

The Blue-legged Grasshopper ranges from the southern reaches of the prairie provinces in Canada to Oklahoma and northern Texas, west to Arizona, Utah, and eastern Idaho. This species is at home in a variety of grassland habitats, from shortgrass prairie like we have here in Colorado to wet meadows at higher elevations. The adults are present from June or July to September.

The first specimen I encountered was on the Fourth of July this year, where it was sitting on the sidewalk barely a block away from my residence in east Colorado Springs. I thought the red and blue colors were quite appropriate for the holiday. I caught the insect and brought it home for better images under controlled conditions, where I could spread the hind wing, too.

The second one I found in a degraded shortgrass prairie at the top of the hill above our neighborhood. So far these are the only two I have seen and I wonder if this is simply not an abundant species. Apparently it is closely tied to its favorite foodplant, Western Wheatgrass, so maybe I should be looking in juice bars and smoothie shops.

It feeds in a very strange manner. The adult grasshopper scales the stem of its target, then snips off a three- or four-inch terminal section of leaf and lets it fall to the ground. The grasshopper then descends to the ground and, manipulating the grassblade with its front legs, eats it from one end to the other.

It is likely that this species is capable of fairly long migrations given its long wings and aerodynamic shape, but more research is needed to learn whether such flights are a regular aspect of its behavior.

Metator pardalinus goes through five nymphal instars before reaching adulthood. Both older nymphs and adults can be gregarious, as recorded in some Montana populations.

A tangle-veined fly, but not Trichopsidea clausa

An interesting enemy of the Blue-legged Grasshopper is Trichopsidea clausa, a species of tangle-veined fly in the family Nemestrinidae. Tangle-veined flies resemble large bee flies in appearance. The adult female fly lays thousands of eggs on elevated objects such as towering weeds or fenceposts. The tiny larvae that hatch are thought to be blown randomly across the landscape. When (or if) they contact a grasshopper, they quickly penetrate the body wall of the host and then live as an endoparasite. Up to 80% of female Bluelegged Grasshoppers have been recorded to be parasitized in some years, and since the fly larvae consume the eggs and soft tissues, the grasshoppers cannot reproduce. The grasshopper sometimes wins, though, sealing off the tiny (0.5 mm) fly larva when it first enters its body.

Sources: Capinera, John, L., Ralph D. Scott, and Thomas J. Walker. 2004. Field Guide to Grasshoppers, Katydids, and Crickets of the United States. Ithaca, New York: Comstock Publishing Associates (Cornell University Press). 249 pp.
Helfer, Jacques R. 1972. How to Know the Grasshoppers, Cockroaches, and Their Allies (2nd edition). Dubuque, Iowa: Wm. C. Brown Company Publishers. 359 pp.
Pfadt, Robert E. 1994. "Bluelegged Grasshopper," Wyoming Agricultural Experiment Station Bulletin 912
"Section I: Biological Control," Grasshoppers: Their Biology, Identification, and Management. USDA (information on the tangle-veined flies).

New Forum Feature

I have created a new forum feature for this blog, through Nabble, because I want to give my followers a way to ask questions that might be unrelated to an existing blog post; and to create a more interactive community here. Thank you in advance for helping me achieve that goal.