Sunday, July 29, 2012

Spider Sunday: Whitebanded Fishing Spider

When Heidi and I went to South Carolina early last May, one of the animals on my “hope to see” list was the Whitebanded Fishing Spider, Dolomedes albineus. It took until the last day of our trip, but I finally found one at the Whack-a-Mole Natural….Wait, that’s not right. The Whatchamacallit National….No….Ah, yes, the Waccamaw National Wildlife Refuge.

The spider was sitting on a piling supporting a floating dock on the Pee Dee River. This is not a small spider. Mature females measure about 23 millimeters in body length (just under an inch). Males average 18 millimeters. Ordinarily, the spider’s mottled gray pattern blends perfectly with lichen-spotted tree trunks where it waits in ambush for an unsuspecting insect or other small animal to wander within striking range.

This particular arachnid perceived motion very well. I ended up chasing it around the piling before it finally settled down. Oddly, it did not bolt, but simply sidled slowly to a new position on the piling. Creepy. Creepy in a creeping, stealthy, smart kind of way.

The white band that gives this spider its common name is the area immediately under the eyes and above the chelicerae (jaws). Maybe it should be called the “whitefaced fishing spider” instead. Sometimes the entire carapace (dorsal surface of the cephalothorax) is white, save for a black spot in the center. Indeed, the color pattern of this species is highly variable. Some individuals are even a mossy green color with darker markings.

This is a fishing spider that really is most common along the edges of aquatic habitats, especially the cypress swamps of the southeast U.S. Its geographic range is from Florida inland and north to the Appalachian Mountains of North Carolina, as well as the Mississippi River basin as far north as Kentucky and southern Missouri.

Not much is known about the life history, habits, and behavior of this species, so your own observations might lend something new to science. At least one researcher, James Carico, noted that adults sometimes congregate in tree holes and crevices, perhaps in a “mating swarm,” though that would be a rare behavior for most arachnids (Carico, 1973).

Like all pisaurids, D. albineus females carry the egg sac in their jaws before eventually creating a “nursery web” amid foliage, bridge beams, or other situations. The female then guards the egg sac and the spiderlings that emerge from it. Once the spiderlings have their first molt outside of the egg sac, they disperse. Their mother then resumes hunting, having fasted during her parental duties.

I consider myself lucky to have seen this magnificent spider, and I hope that you will add it to your own “must see” list of arachnids. You do have one of those by now, right?

Sources: Carico, James E. 1973. “The Nearctic Spiders of the Genus Dolomedes (Araneae: Pisauridae),” Bull Mus Comp Zool 144: 435-488.
Gaddy, L.L. 2009. Spiders of the Carolinas. Duluth, Minnesota: Kollath+Stensaas Publishing. 208 pp.
Howell, W. Mike and Ronald L. Jenkins. 2004. Spiders of the Eastern United States: A Photographic Guide. Boston: Pearson Education. 363 pp.

Wednesday, July 25, 2012

Wasp Wednesday: Not Wasp VIII

This week, July 23-29, 2012, is National Moth Week, but if you only go out looking for them at night, you are going to miss some of the most amazing moths of all. Many species of moths are diurnal, visiting flowers for nectar, or simply seeking host plants for their caterpillar offspring.

Beyond the simple fact that there are moths that fly in broad daylight, many are mimics of other insects, especially wasps, and they can be very convincing. I found the specimen above along the shores of the Arkansas River just west of Cañon City, Colorado on July 15. At first I thought it was a miniature tarantula hawk, or at least some other kind of colorful spider wasp, but it wasn’t flying quite right. When it eventually settled, I was even more excited. It is a “clearwing moth” in the family Sesiidae, specifically Alcathoe pepsioides. Special thanks to William H. Taft of DeWitt, Michigan for the species identification via Bugguide.net. The genus is found only in the New World tropics, north into the southern United States. The five species found north of Mexico are not commonly found or collected. Males like the one pictured here, each have a single tail-like appendage trailing from the tip of their abdomen. This is a good approximation of the dangling legs of a wasp. Caterpillars of these moths are borers in the stems of Clematis.

Not all sesiids are as large and spectacular. Heidi spotted the specimen above on a flower in a meadow at an elevation of over 10,000 feet in the Maroon Bells-Snowmass Wilderness near Schofield Pass in Gunnison County. It remains unidentified, as many specimens can only be determined to genus and species by examination under a microscope. It could easily pass for a mason wasp (Vespidae: Eumeninae) if one did not know better.

Clearwing moths are not the only moths to mimic wasps. Leaf-skeletonizer moths, family Zygaeidae, could be mistaken for certain spider wasps, too. The Western Grapeleaf Skeletonizer, Harrisina metallica, is deep metallic blue in color, like many wasps in the Pompilidae. Their larvae are caterpillars that reduce grape leaves to lacy shadows of their former selves. Still other zygaeids mimic the toxic net-winged beetles of the family Lycidae. Those moths are frequently bright red or orange and black.

Certain tiger moths in the family Erebidae (subfamily Arctiinae, which once ranked as its own family) are likewise thought to be wasp mimics. The genus Ctenucha is perhaps the most widespread and frequently encountered, but there are even more astounding mimics in the subfamily, even some with clear wings. The Virginia Ctenucha, Ctenucha virginica, shown below, is common east of the Rocky Mountains.

Larger moths can also be wasp mimics. The Nessus Sphinx moth, Amphion floridensis, is possibly a mimic of the Eastern Cicada Killer Wasp. The moth flies during the day, but especially at dusk, often hovering in front of flowers as it taps the nectar inside each blossom. Widespread east of the continental divide, it feeds on the leaves of grape and cayenne pepper plants as a caterpillar.


photo courtesy of Diane Wilson via Bugguide.net

Not all day-active moths are mimics, of course. Some really do look like moths. Those in the genus Schinia are notoriously colorful, but their wardrobe often helps to camouflage them on the flowers where they rest or seek nectar. There are at least 123 species in North America north of Mexico, so at least a few are bound to occur in your own neighborhood. The caterpillars eat the flowers (and later the seed pods) of their host plant. Not all species of Schinia are diurnal, so look for them at lights at night, too.

Nature can be a complex and confusing Mother, so don’t get too discouraged if you can’t tell a moth from a wasp from a beetle or a fly. Getting fooled only means that Nature’s plan is working.

Sources: Beadle, David and Seabrooke Leckie. 2012. Peterson Field Guide to Moths of Northeastern North America. Boston: Houghton Mifflin Co. 624 pp.
Covell, Charles V., Jr. 1984. A Field Guide to Moths Eastern North America. Boston: Houghton Mifflin Co. 496 pp.
Krogmann, Lars and Hans Riefenstahl. 2004. “a new species of Alcathoe H. Edwards, [1882] (Lepidoptera: Sesiidae) from Mexico,” Deut Entomol Z 114(5): 195-197.
Powell, Jerry A. and Paul A. Opler. 2009. Moths of Western North America. Berkeley: University of California Press. 369 pp.

Sunday, July 22, 2012

Spider Sunday: Hammock Spiders

What could be more relaxing on a Sunday afternoon than lounging in a gently-swaying hammock in the backyard? Well, don’t ask any of the hammock spiders in the genus Pityohyphantes. Their “hammock” is not for relaxing but for capturing insect prey.

Hammock spiders are in the sheetweb weaver family Linyphiidae, and their webs are more often slightly convex rather than concave. The silken platform is suspended by a maze of threads above it, it just doesn’t sag very often. There are sixteen species in North America, mostly occurring in the coniferous forests of the west and north. Shown here are two specimens from western Massachusetts, and one from the Front Range in Colorado. The very name Pityohyphantes is Greek for “pine weaver.” Look for their webs in hardwoods, too, usually in foliage and well off the ground.

I was surprised to find the Colorado specimen shown below hanging in the middle of its web, upside down beneath the sheet. Usually, these spiders conceal themselves on the underside of foliage on the periphery of the snare. They may also construct their webs on fences or the exterior of buildings and other manmade structures.

The spiders themselves are not particularly large. Mature females are around 5-7 millimeters in body length, the males slightly smaller. Mating takes place in the spring, at least in the species Pityohyphantes costatus. The female attaches her egg sac to a twig or other object on the edge of the web. Apparently both adults and immature specimens may pass the winter under bark, or stones on the ground.

Hammock spiders are fairly easily recognized by the consistent pattern on the abdomen, a brown or reddish jagged-edged band down the middle of the back, on an ivory background. Reliable identification of the species can only be accomplished by examining the external genitalia.

How do you tell hammock spiders (or any sheetweb weaver for that matter) from cobweb weavers? One clue is the legs. Cobweb weavers have legs free of spines, whereas sheetweb weavers generally have prominent setae on the legs. Obviously, the webs can be a clue as well, though some cobweb weavers like Steatoda do spin a sheet-like web with a maze of tangled lines above and below their webs.

I have not found hammock spiders to be nearly as abundant as other sheetweb weavers like the Bowl and Doily Spider or various dome spiders, but I haven’t been looking intensely for them, either. See if you can find them around your own neighborhood or local park. Of course, you’ll have to get out of your own hammock to do that….

Sources: Kaston, B. J. 1978. How to Know the Spiders (Third Edition). Dubuque, Iowa: Wm. C. Brown Company Publishers. 272 pp.
Moulder, Bennett. 1992. A Guide to the Common Spiders of Illinois. Springfield, Illinois: Illinois State Museum Popular Science Series, Vol. X. 125 pp.
Weber, Larry. 2003. Spiders of the North Woods. Duluth, Minnesota: Kollath+Stensaas Publishing. 205 pp.

Thursday, July 19, 2012

Summer 'hoppers Part II

A couple of weeks ago I blogged about summer grasshoppers in the immediate vicinity of Colorado Springs. Since late May I have also had opportunities to travel to other parts of Colorado and found some very interesting species in those locations, too.

Before I leave the city limits in the virtual sense, let me add two other species to the list. The Big-headed Grasshopper, Aulocara elliotti (above), is technically one of the slant-faced grasshoppers, but it has a very round face. It lives in the entire western half of the U.S. and adjacent southern Canada, ranging as far east as extreme western Iowa and Minnesota. It also slips far into the middle of Mexico. Look for it mostly in shortgrass prairies and desert grasslands with sparse vegetation. Even so, I encountered it at higher elevations in conifer woodlands. Go figure. The big head, and bright blue hind tibiae, helps identify this species, which can easily be mistaken for a band-winged grasshopper. It can occasionally reach pestiferous population levels and become damaging to crops.

The Western Spotted-wing Grasshopper, Cordillacris occipitalis, is unquestionably a slant-faced grasshopper. The long, white antennae are pretty distinctive. I noticed this species into late fall as well. This is another shortgrass prairie species with a range similar to the Big-headed Grasshopper. It is likewise prone to population booms that can make it a rangeland pest.

Farther out on the plains in El Paso County, one finds most of the grasshoppers found in city vacant lots, but in greater numbers. You also get other species like the big Coral-winged Grasshopper, Pardalophora apiculata, shown below. It ranges from deep into western Canada and south through northeast Washington, eastern Wyoming and Colorado, and south through Oklahoma, Missouri, Tennessee, and northward into eastern Canada. It is a mostly early- to mid-summer species in the adult stage. Females are heavy-bodied and reluctant to fly, which may explain why I was able to get so close to this one, in the middle of a road. This grasshopper gets its name from the orange or red hind wings, bordered with a dark brown or black band.

A road trip between Cañon City and Pueblo that took me into more rangeland produced a trio of really spectacular grasshoppers. Just outside the Custer County Conservation District boundary, I spied a single specimen of the Three-banded Range Grasshopper, Hadrotettix trifasciatus.

Large, and strikingly marked with three black bands across the front wings, it is hard to miss. Still, once it lands, it walks into dense grasses, making it difficult to get an image. Note the long, black antennae, and bright orange hind tibiae. The hind wings are pale yellow with a noticeable black band. This is a species of the Great Plains from Canada to Mexico, west throughout most of Arizona. It prefers to eat broadleaved herbs, but will stoop to feeding on grasses occasionally.

The largest grasshopper in Colorado is the Plains Lubber, aka “The Homesteader,” Brachystola magna, and I found one of those later on the trip. While the other grasshoppers profiled here belong to the family Acrididae, the Plains Lubber belongs to the family Romaleidae, which includes the Eastern Lubber Grasshopper and the Horse Lubber. Brachystola is a wingless insect, even as an adult. It measures 40-60 millimeters, females on the higher end of that spectrum. It comes in a variety of colors, too. Some are green, some brown, some pinkish, some even bluish.

The eggs of this species, typically laid in poor soil along roadsides and marginal rangeland, apparently pass through two winters before hatching. This may account for population booms and busts. While it feeds mostly on the foliage of sunflowers and various other broadleaved plants, it is also omnivorous, feeding on dead insects encountered in its wanderings. It will even eat road-killed members of its own kind. Large numbers of dead lubbers can grease the pavement, creating a real road hazard.

By far the most amazing grasshopper I saw was a by-product of trying to follow the Plains Lubber. My jaw dropped when I spotted a red, white, and blue Rainbow Grasshopper, Dactylotum bicolor. Much smaller than the lubber at only 24-32 millimeters, this species more than makes up for its size with its color pattern. This is another grasshopper of the Great Plains, from Saskatchewan to Mexico. Like the lubber it is wingless in all life stages, and feeds mostly on low-growing broadleaved plants. The colors and pattern can vary from specimen to specimen and area to area, but it is always a stunning sight.

I can hardly imagine any other grasshoppers that would be as thrilling to see as those last three, but I’m still in search of the “Green Fool Grasshopper,” so stay tuned.

Sources: 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 (Second Edition). Dubuque, Iowa: Wm. C. Brown Company Publishers. 359 pp.

Wednesday, July 18, 2012

Wasp Wednesday: Hoplisoides nebulosus

I continue to be pleasantly surprised by the diversity of wasps here on the Front Range in Colorado Springs. The multitude of plant communities, and ecosystems that change with even a moderate rise in elevation, mean there is an abundance of niches for various members of the Hymenoptera. Last Tuesday, July 10, while prowling a vacant lot in my neighborhood, I discovered yet another genus in the family Crabronidae: Hoplisoides.

The female wasp, about 8-10 mm in length, was scratching the sandy soil at my feet when I spotted her. Initially, I thought she was a mason wasp, owing to their behavior of scraping dry soil for use in their mud nests, and the splayed wings that are characteristic of eumenids. Closer inspection of my first image revealed her to be a crabronid wasp in the genus Hoplisoides, with trademark spotted wings.

The wasp took off but flew just above the ground and eventually landed again at a spot of disturbed sand where she had apparently started digging earlier. She resumed excavating that spot and I spent at least half an hour shooting images each time she emerged from the burrow to deposit her diggings and groom the entrance to disguise the location of her nest. The behavior of digging in several spots before selecting one site to finish is apparently not unusual (Evans, 1966)

There are about eighteen species of Hoplisoides in North America north of Mexico, collectively distributed over the entire continent, including Alaska. The bulk of the species are western. Globally, the genus is found everywhere except Australia.

Most North American species hunt adult and immature treehoppers in the family Membracidae (example below) as food for their larval offspring. Females dig relatively short burrows in sand, the tunnels terminating in one or several underground cells.

“My” wasp was preparing just such a nest, and after completing it filled in the entrance, effectively obliterating all evidence of her work. She made a low “orientation flight” before taking off to hunt prey. I only hope that she did not use me as a landmark. I could hear her “voice” later: “Dang. I seem to remember some big hulking object right here….”

She entered and exited her burrow head first, in contrast to most burrowing wasps that back out of the nest during its construction. The typical burrow descends at an angle of 45-70° for roughly ten centimeters and a depth of about six centimeters. The terminal cell or cells are about 9-11 millimeters long, and 7-9 mm in diameter. An average of 10-15 paralyzed treehoppers go into each cell, but that can vary dramatically depending on the size of each prey item. The larger the prey species the fewer are needed. A single egg is laid on the last victim to go into the cell. Most female wasps make at least a handful of individual nests in their lifetime. It should be noted that the above description pertains to Hoplisoides nebulosus, found mostly in the eastern U.S., and the species depicted here.

Hoplisoides do not spend much time on the final closure of their burrows, so are often victimized by parasites. The cuckoo wasp Elampus viridicyaneus is one such enemy. So are crabronid wasps in the genus Nysson. The velvet ant Dasymutilla vesta may be another parasite; and the “satellite flies” of the family Sarcophagidae (Senotainia trilineata being one) are an ever-present threat lurking in the vicinity of nests.

You will rarely see Hoplisoides on flowers, but you might find them around aphid colonies. They are fond of “honeydew,” the sugary liquid waste product secreted by aphids. Catalpa trees and oak trees are often good places to look for aphid colonies. The constant rain of honeydew will ake the leaves appear glossy or sweaty. Otherwise, encounters with these treehopper hunters are pretty much serendipitous.

Note: The wasp specimen imaged here has since been identified as Hoplisoides nebulosus spilopterus by Matthias Buck at the Royal Alberta Museum in Edmonton. Thank you, Dr. Buck!

Sources: Evans, Howard E. 1966. The Comparative Ethology and Evolution of the Sand Wasps. Cambridge: Harvard University Press. 526 pp.
O’Neill, Kevin M. 2001. Solitary Wasps: Behavior and Natural History. Ithaca, New York: Cornell University Press. 406 pp.

Sunday, July 15, 2012

Spider Sunday: Pike Slender Jumper

You never know what you are in for when you agree to help with a “bug event” at your local park, nature center, museum, or zoo. This past Wednesday, July 11, I agreed to help out at the “sweep net station” during the “Big Day for Bugs” event at the Fountain Creek Nature Center in Fountain, Colorado. It was fun helping kids and their parents and guardians discover insects and spiders, and in the process I was surprised by one find in particular.

A part-time naturalist at the nature center decided to try his own hand at sweeping, and went out into a field adjacent to our table under the “grandfather cottonwood” tree. He deliberately swept through a patch of horsetails (Equisetum sp.) that rose amid the dry grasses and herbs. Fountain Creek Regional Park includes a natural riparian habitat and several artificial ponds, but the horsetails were not terribly close to water. Anyway, when he dumped his catch, one spider stood out immediately.

Among the usual crab spiders (Thomisidae family), long-jawed orb weavers (Tetragnathidae), and other jumping spiders (Salticidae), were several specimens of the bizarre Pike Slender Jumper, Marpissa pikei. “Slender” is being generous. They put Twiggy to shame and look to be on the verge of anorexia. I managed to fire off a few images of two of the more impressive male specimens before they found their way off the table and back into the field.

Marpissa pikei ranges from the eastern U.S. and southeast Canada west to Nebraska and Arizona. I guess you can add Colorado to the map, too. These are not large spiders. Mature females measure 6.5-9.5 millimeters in body length, and males 6-8.2. The first pair of legs, however, are easily as long as the entire body, so the animal looks twice as big. Those heavy front legs are not the ones used to launch the arachnid in its jumps, but are used mostly to grab prey. They are not even used in walking, the spider using its other six legs for mobility.

The shape, pattern, and posture of the Pike Slender Jumper camouflages it very well as it waits in ambush in tall grass for a potential insect meal to come within striking distance. They are very alert and agile, as demonstrated in this video by Richard Walton.

Males make good use of those long legs in courtship displays, raising those limbs vertically, and elevating the abdomen to get a female’s attention.

Mature individuals of Marpissa pikei can be found from spring through fall, and even in the winter in Florida. The species is perhaps more abundant in arid habitats like beach grasses, dunes, and prairies than in other grassland communities.

Sources: Barnes, Robert D. 1958. “North American Jumping Spiders of the Subfamily Marpissinae (Araneae, Salticidae),” Am Mus Novit No. 1867: 1-50
Guarisco, Hank, Bruce Cutler, and Kenneth E. Kinman. 2001. “Checklist of Kansas Jumping Spiders,” Kansas School Naturalist vol. 47(1)
Gaddy, L.L. 2009. Spiders of the Carolinas. Duluth, Minnesota: Kollath+Stensaas Publishing. 208 pp.
Howell, W. Mike and Ronald L. Jenkins. 2004. Spiders of the Eastern United States: A Photographic Guide. Boston: Pearson Education. 383 pp.

Wednesday, July 11, 2012

Wasp Wednesday: Wasp vs. Bug

Back when I wrote about the Brown Marmorated Stink Bug, Halyomorpha halys, it was an introduced species from Eurasia that was no more than an indoor nuisance pest in the U.S. in the fall and winter. It has since ballooned into a certifiable agricultural pest in apple and peach orchards, and also vineyards. So panic-stricken are government officials that congress is attempting to pass a $831,000 “farm bill” to find ways of combating the bug. Enter a native wasp, Bicyrtes quadrifasciatus, pictured below.

The wasp is a type of “sand wasp” that preys on true bugs in the order Hemiptera, suborder Heteroptera. Each female wasp digs a burrow in sand, and stocks the cell at the end of the tunnel with paralyzed true bugs that will serve as food for a single larval offspring. Turns out that the Brown Marmorated Stink Bug has become a favorite target of the wasp, which hunts the immature stages of the pest (see figure below).

Alex Surcică has noticed this trend, and wants to document the efficiency of the wasps in controlling the bug. To that end he recently posted this message on his Facebook page:

"Seeking collaborators interested in collecting data on the nest provisioning of the sand wasp, Bicyrtes quadrifasciatus. This solitary (read non-aggressive) wasp occurs throughout North America, east of the Rocky Mountains, and it nests only in sand, along water ways or in sand volleyball courts and kids sandboxes. For making observations, one needs a garden trowel, pen, and notebook. The results of this citizen-science project will be used to assess the role the sand wasp plays in controlling the Brown Marmorated Stink Bug, a multi-million dollar pest. If interested, reply and I will send you more info. Please take an extra moment and share this with your FB friends. Thank you!"

Alex also posted a series of images on his “Bees, Wasps, and Other Beneficials” Facebook page that details how he painstaking excavates Bicyrtes nests to census the number of each prey species taken by the wasp:

“When I'm collecting data on the nest provisioning of the sand wasp, I'm waiting to see a female with her paralyzed prey entering her nest. While she's inside (sometimes can take minutes), I use a twig to mark the nest. I always position the twig three inches to the left of the nest entrance, and at a slight angle that will indicate later on where tunnel was leading to. Once the nest is marked, I search for other nests. Female sand wasps tend to initiate many nests but do not always end up using them. Therefore, I always mark only the nests that had females with prey entering them.”

I heartily applaud Alex for attempting this endeavor; and I encourage my readers to become part of his effort. Bicyrtes quadrifasciatus is common over most of its range, and several females may nest in the same general vicinity. So, once you find one nest, you are likely to find others.

Meanwhile, the U.S. Department of Agriculture is considering importing a parasitic wasp from the geographical area overseas where the stink bug is native. Introductions of parasites as “biocontrols” have not always ended well. There is the risk that the “new” parasite from abroad will find our native, non-pest stink bugs as acceptable a host as the Brown Marmorated Stink Bug. Maybe the native bugs would be even more attractive to the parasite. That kind of scenario has happened before.

I thank Alex Surcică for allowing the use of his images in this post as well. Do check out his “Bees, Wasps, and Other Beneficials” Facebook page for more stunning photos.

Sunday, July 8, 2012

Summer 'hoppers Part I

Note: Today’s “Spider Sunday” appears on my companion blog, Sense of Misplaced, for reasons that will become clear if you visit that site.

Here on the Front Range and high plains of central Colorado, it seems that grasshoppers are ever-present and the diversity ever-changing. The continuing drought has no doubt contributed to the overall abundance of Acrididae (short-horned grasshoppers) this year. I was finding adult Speckle-winged Rangeland Grasshoppers, Arphia conspersa, on the last day of February, and it has only gotten more amazing since.

Easily the most exciting discovery I made was spotting the Crowned Grasshopper, Trachyrhachys coronata. I imaged the female shown below on June 2, just up the street in a vast vacant lot with very short grasses and herbs, and small, widely scattered elm trees. I was completely perplexed by the leopard-spotted pattern on what is really a pretty slender animal. Most leopard-spotted grasshoppers are very large and robust.

Enter David Ferguson, a grasshopper expert who lends his knowledge to Bugguide.net. I e-mailed him the image above and pleaded for help. He recognized it as a female Crowned Grasshopper, a seldom-seen species. Indeed this picture, and the one of a male taken on June 29 (below) may be the only images of live specimens in existence, at least in the digital age. No wonder I couldn’t find a match on Bugguide or elsewhere.

The most common species of Trachyrhachys is T. kiowa, shown below. Note the blue hind tibia. When it flies, the hind wings are either clear or yellow, with little or no contrasting black band. Hard to note such details when they explode from underfoot and then quickly land again. This one is on the wing right now, a very common species.

The enormous female Red-shanked Grasshopper, Xanthippus corallipes, shown below, is more typical of the leopard-spotted grasshoppers. She keeps her most vibrant colors mostly concealed. The back of her head is blue, and the inner surface of her hind femora (“thighs”), and the entirety of her hind tibiae, are bright vermilion. Her hind wings, visible only when she is flying, are bright yellow with a black band.

By the side of the road at a major intersection I found the slender little ‘hopper below, Derotmema haydeni. It was so hot that it was elevating itself on only four of its six legs, and headed for the shade of a small plant at the first opportunity. This species can have yellow or red hind wings with a black band.

In contrast to the colorful band-winged grasshoppers described above are the super-camouflaged “slant-faced” grasshoppers that mimic grasses, not the surface of the soil. Slant-faced grasshoppers are generally striped, whereas band-winged grasshoppers are speckled or spotted. The Velvet-striped Grasshopper, Eritettix simplex, is anything but simple. It has enough variation to convince you that there are several species rather than just one. The typical form is shown here (brown and white):

They also come in green and brown (and white):

Wait, there’s more. This specimen that I found on the door jamb of my apartment I had pegged as Opeia obscura, but no-o-o-o, just another Eritettix simplex.

The Velvet-striped Grasshopper is surely one of the most abundant species here in Colorado Springs. Virtually every vacant lot has them.

An even more handsome species is the Striped Slant-faced Grasshopper, Amphitornus coloradus. It favors bunchgrasses and I only found it in one little patch amid yucca and prickly pear cacti.

Stay tuned. Last Monday I went through the wilderness between Cañon City and Pueblo and turned up some incredibly stunning grasshoppers. You literally have not seen anything yet!

Thursday, July 5, 2012

Wasp Wednesday: Stizoides renicinctus

One of the cool “surprise bugs” from the ”wasp tree” was a kleptoparasitic wasp (I’ll explain that term below), Stizoides renicinctus. This insect is so obscure that it has no common name in English, but that doesn’t take anything away from its unique life history.

S. renicinctus is one of only two species in the genus occurring in North America. Globally, there are thirty species in the genus, most found in Africa, Mediterranean Europe, the Middle East, and India. The only other species in the U.S. is S. foxi, restricted to Arizona (and south into Mexico).

Field marks that help to identify S. renicinctus include an all black body with a red or orange band on the second dorsal abdominal segment (tergite), dark wings with translucent wingtips, and an overall elongate appearance. Both genders are nearly identical in appearance and size, at about 16-18 millimeters.

One usually encounters the males taking nectar from flowers. I was surprised at the fair number of them on the saltcedar tree during the latter half of June here in my Colorado Springs neighborhood. I have also seen this species in southern Arizona, coming to the blossoms of Seepwillow, Baccharis salicifolia in dry arroyos or along rivers.

Females are mostly busy seeking hosts for their offspring. The term “kleptoparasite” refers to an animal that essentially raids the refrigerator of its host organism. That means the parasite feeds on the material stored as food by its host. S. renicinctus is known to exploit the food caches of other solitary wasps in the genera Prionyx and Palmodes. Female Prionyx hunt grasshoppers (Acrididae), while Palmodes hunts katydids (Tettigoniidae). The wasps dig burrows and stock at least one prey item per cell that a single larva will consume to grow and mature into an adult wasp of the next generation. The female Stizoides renicinctus locates the closed burrow of a host, digs it open, destroys the host egg, and replaces it with one of her own. The larva that hatches will eat the food the host mother wasp took such care in providing.

It has been noted that S. renicinctus is not always solitary. Individuals will gather in “sleeping” clusters on vegetation at night. They apparently do this in the face of impending inclement weather, too. I found a loose aggregation forming in the saltcedar bush on the afternoon of June 16 as storm clouds began to gather. These wasps will sometimes be found amid sleeping clusters of other solitary wasps as well.

These wasps are quite efficient parasites, as documented by I. LaRivers in a 1945 paper in American Midland Naturalist. He found the species parasitizing Palmodes laeviventris in Elko County, Nevada. The Palmodes were doing local agriculture a service by slaying Mormon crickets (a type of wingless katydid), but the Stizoides wasps were also reaping the benefits. LaRivers estimated a parasitism rate of about 7.5 percent, which he extrapolated to roughly 10,000 destroyed Palmodes nests in about 350 square yards.

Ok, so Stizoides is an outlaw of the Old West (it actually ranges from Michigan and Wisconsin south to North Carolina and west to Alberta, British Columbia, California, Arizona, and Mexico). I would like to think that seeing a good number of specimens means that there is also a thriving population of host wasps. That in turn means abundant grasshopper prey, and thus a healthy habitat.

Be on the lookout for Stizoides where you live, and see if you can find one in the act of finding a host. You may discover a relationship previously unknown to science. You just never know.

Sources: Bohart, R.M. and A.S. Menke. 1976. Sphecid Wasps of the World: A Generic Revision. Berkeley: University of California Press. 695 pp.
Evans, Howard E. and Kevin M. O’Neill. 2007. The Sand Wasps: Natural History and Behavior. Cambridge, Massachusetts: Harvard University Press. 360 pp.

Sunday, July 1, 2012

Spider Sunday: Longjawed Orb Weavers

The longjawed orb weavers in the family Tetragnathidae are among the most abundant of summertime spiders. Today I’ll focus on the genus Tetragnatha. There are fifteen species collectively distributed across the entire North American continent, and I’ll bet you can find at least one near you.

The tetragnathids get their common name from the fact that many species have extraordinarily long chelicerae (jaws) and fangs. Their entire bodies, and legs, are long for that matter. Their narrow shape and resting posture helps to camouflage them, even if they are sitting in the middle of their webs.

Longjawed orb weavers construct orb webs in a horizontal plane, or close to it. This helps differentiate them from the majority of orb weavers in the family Araneidae that create webs on a vertical axis. I find that longjawed orb weavers seem to fit in one of two categories: small species that live in meadows and fields; and larger species that make their webs over water. There is naturally some overlap, but meadows and riparian corridors are where you are most likely to encounter them.

They are tolerant of each other’s company, too, often building individual webs in close proximity to others of their kind. This behavior reaches its zenith in Tetragnatha guatemalensis.

That species is essentially social, and capable of spinning communal webs that can stretch for acres. Remember that enormous web in Lake Tawakoni State Park in Texas, back in 2007? That was the work of thousands of T. guatemalensis spiders. I found a similar situation, on a smaller scale, at Sweetwater Wetlands in Tucson, Arizona in late October of 2010 (see below). It is difficult to communicate the vast expanse of silk, but it certainly exceeded what tent caterpillars can do.

Those species that live in meadows usually occupy the hub of their webs, but their long bodies, complemented by long legs held close to together, disguise them as broken bits of grass stems. Many are straw-colored and they blend in quite well. When disturbed, they dash out of their webs to hug a grass stalk, merging almost imperceptibly with the plant.

Water-loving species usually sit on the perimeter of their webs, again hugging the substrate, often a twig or piece of emergent vegetation that anchors one corner of their web. The orbs usually have the spiral widely spaced. Still, the snare is very effective in trapping adults of aquatic insects like midges, gnats, and mayflies that emerge directly from the water into the air. The horizontal web intercepts them on the way up.

Mature tetragnathids, depending on the species, can measure from 5-16 mm or so in body length. The spindly legs make them seem even larger. Males are usually the (slightly) smaller gender. During mating, both sexes grasp each other’s jaws. Males may have spurs on the chelicerae to receive the female’s fangs, presumably to avoid fatal results from the whole affair.

Females lay their eggs in egg sacs, and those silken packages can vary in appearance by species. Some are adhered closely to a twig or other object, blending in with the substrate. Others, like the one above that I found in south Texas, are suspended on the periphery of the web. Once the web itself is long gone, the remaining egg sac can be a puzzling object for the naturalist to make sense of.

Identifying longjawed orb weavers to species is an inexact science based in large part on the genitalia; and also on the relative spacing of the eyes, and the length of the jaws relative to the length of the carapace (top of the cephalothorax). It is enough to simply appreciate their diversity in my own opinion. One species that is easy to recognize is the emerald green Tetragnatha viridis, found in the eastern U.S. and adjacent southern Canada. There is no mistaking it for any other.

See if you can spot some of these unique spiders near your home, or the next time you go down by the river or lake. You might also want to thank them for helping diminish the populations of midges, mosquitoes, and other insects that annoy you at this time of year.