A Couple of Weirdos

My last post here focused on the joys of National Moth Week, but what I neglected to mention was the added benefit of other insects being attracted to blacklights. Sometimes you get strange and significant surprises at your ultraviolet beacon. This is the story of two of those.

Clown beetle, Ulkeus intricatus, from Chico Basin Ranch

During our first moth week event at Chico Basin Ranch on July 21, we were all taking images of the moths that were drawn to our lights. There were plenty of other insects, too, like true bugs, flies, even a few wasps, plus lacewings, antlions, and beetles. I tried to document most everything, but it was not until I began editing my pictures that I noticed something spectacularly wierd. In one corner of an image of a moth was a beetle I recognized instantly as a "clown beetle" in the family Histeridae, but it had strange flanges on its legs and was a lot more bristly and "groovy" than the usual hister beetle.

It was reddish in color, too, while nearly all other clown beetles are jet black. I was aware that some clown beetles are found only in association with ants, and so I began looking at various species in the subfamily Hetaeriinae. Sure enough, up popped Ulkeus intricatus as the most likely suspect.

Legionary ants, Neivamyrmex sp., hosts of the clown beetle

So, now I begin researching this species, or at least the genus, to find out what its life history is like. It turns out that it is found only in the company of legionary ants in the genus Neivamyrmex, which makes things stranger still. Legionary ants are in a group of ants that includes army ants. They are nomadic, and mostly nocturnal, raiding the nests of other ants to prey on the larvae and pupae. This explains why the beetle was flying just after sunset: It was looking for a party of legionary ants and got distracted by our UV lights.

Exactly what the beetle does with, or to, the ants is largely unknown. My references say that the beetles are "guests" of the ants, which could mean anything from mutualism to kleptoparasitism (mutually beneficial relationship versus stealing the ant's food), or something else entirely. Exactly how the beetle would complete its life cycle if its host has no nest raises questions, too, though Neivamyrmex colonies are known to be sedentary over the winter.

Male legionary ants like this one fly to lights at night, too

There are six recognized species in the genus Ulkeus in the U.S., collectively ranging from North Carolina and Tennessee to Florida and west to Texas and Arizona. Five of those species are yet to be named and described, so I may be jumping the gun to assign a species to this one, especially since I never saw the thing let alone collected it. For all I know it is a seventh species.

Braconid wasp, Chrysopophthorus americanus

My wife and I put out a blacklight near Lyons, Colorado on July 22, despite cool and damp conditions, and among the many insects that flew in was a small, ghostly-looking wasp. I recognized that it was probably a member of the family Braconidae, wasps parasitic on other insects, but was baffled after that. Thankfully, there is Bugguide.net, and I started browsing the images to see if anyone else had recorded this wasp and, if so, was it identified.

Lo and behold, there it was, identified as Chrysopophthorus americanus. That almost never happens, being able to get a species identification that way. What's more, I learned that this wasp is a parasite of adult green lacewings (Neuroptera: Chrysopidae). Talk about a specialized niche. Since lacewings are often attracted to lights, it stands to reason that their parasites would be, too. Apparently the female wasp inserts her egg into the abdomen of the lacewing. The larva that hatches then feeds as an internal parasite inside the lacewing, eventually exiting to pupate.

Those beautiful emerald eyes!

What a wacky couple of "bugs." That is what I love about entomology, and natural history in general: You never know where one observation is going to take you, how one species intertwines with others....It is supposed to be a mild night here on October 21 and I am half-tempted to put the sheet and the blacklight out.

Sources: Caterino, Michael S. and Alexey K. Tishechkin. 2009. "A New North American Genus of Hetaeraiinae (Coleoptera: Histeridae), with Descriptions of Six New Species from the U.S.A. and Mexico," Zootaxa, 2311: 1-18.
Maxwell, John R., et al. 2008. "Species Chrysopophthorus americanus," Bugguide.

More Beetles from Bones

Last week I wrote about a few beetle species that I recovered from nearly dry bones here in Colorado Springs. I now have an update, plus additional species found in carrion on a recent trip to a private ranch northeast of Pueblo. It is interesting to note the succession of carrion beetle fauna over time; and the differences in diversity depending on whether the carcass is a large mammal, small mammal, bird, herp (reptiles and amphibians), or fish.

I went back to the bones I found earlier, and discovered some changes as of April 18. I spotted another Northern Carrion Beetle, Thanatophilus lapponicus, before it quickly disappeared, and more dermestids that I previously identified as Dermestes marmoratus. However, a different, smaller species was now more abundant.

Hide and Tallow Beetle, Dermestes talpinus?

I have decided I cannot readily conclude what species are involved here. Twelve species of Dermestes are recorded from Colorado, many of which look nearly identical to each other. The smaller species present on the bones appears to be the Hide and Tallow Beetle, D. talpinus. It is covered in gold or coppery scales on the pronotum (top of thorax), and silvery scales on the elytra (wing covers).

I also found a single specimen of yet another species that is possibly the Fringed Dermestid, D. frischii.

Dermestes frischii?

My wife and I travelled to Chico Basin Ranch on Monday, April 21, mostly seeking spring migrants of the feathered variety. This is a sprawling, working ranch that straddles El Paso and Pueblo Counties, and is managed for both livestock and native wildlife.

Unfortunately, one of the first birds we came across was a deceased Bobwhite quail. Turning it over revealed a shocking diversity of beetle life.

Rove beetles in the family Staphylinidae are predatory, and the ones that visit carrion feed mostly on fly maggots. They are easily recognized by the shortened elytra (wing covers), and are perhaps reminiscent of earwigs.

Hairy Rove Beetle, Creophilus maxillosus

The Hairy Rove Beetle, Creophilus maxillosus, is enormous by staphylinid standards, measuring 11-23 millimeters. These insects fly well, but quickly dig themselves out of sight when uncovered.

Rove beetle, Philonthus politus

Another rove beetle species, Philonthus politus, was also present. It is much smaller, about 10 millimeters. Special thanks to Philip Howe and Max Barclay for suggesting the genus, and Adam Brunke for volunteering the species. Facebook interest groups are a wonderful thing.

Sexton beetle, Nicrophorus sp.

Two species of the family Silphidae were also under the bird carcass: Thanatophilus lapponicus again, and one of the sexton beetles, Nicrophorus sp. Sexton beetles, also known as burying beetles, are big (11-22 mm or so), stocky, and strong. They often work in pairs to dig under the corpse of a small animal, sinking it into the ground. They then chew the carcass into a literal “meatball,” and the female then deposits a small number of eggs in a crater atop the food ball. She’ll chew up small bits of meat and feed them to her larval offspring, cleaning the food of mold and other potential contaminants in her spare time.

Clown beetle, Saprinus lugens

Clown beetles in the family Histeridae are small, spherical, highly-polished insects that play dead or dig when disturbed. They are predatory on other small insects found in carrion, dung, and other unsavory mediums. This one is Saprinus lugens, a common and widespread species measuring 5-8 mm. Thanks to Alexey Tishechkin for the species identification.

Male Scooped Scarab, Onthophagus hecate

Many dung beetles will also visit carrion, such as the little “Scooped Scarab,” Onthophagus hecate. Males have a broad, forked horn projecting over their heads from the top of the thorax. They battle each other for the right to mate with a female. At only 6-9 millimeters, O. hecate is one of the smaller dung beetles.

Hide beetle, Trox sonorae

Last but not least, were cryptic “hide beetles,” Trox sonorae, in the family Trogidae. They are closely allied to scarab beetles. Trogids are rough in texture, and usually so caked in debris as to be nearly unrecognizable as insects. They also play dead so convincingly as to be easily dismissed as living creatures. They freeze in a random, rigid posture when disturbed. This species is only 8-11 millimeters in size, which only makes it even harder to spot. Trox consume dried skin, feathers, and other material when carcasses are in the last stages of decay.

Silphid carrion beetle larva

Dermestes larva

Later in the day, Heidi and I came across the remains of a large livestock mammal, and virtually none of the beetles found on the dead quail were on this much larger vertebrate. Instead, it was carrion beetle larvae, dermestid larvae and adults, and Red-legged Ham Beetles, Necrobia rufipes. There are three common species of Necrobia, all in the family Cleridae. While most clerids are predators, Necrobia adults and larvae actually do feed on carrion, cured meats, and other dried animal products. They can be pests in museums and taxidermy businesses. Ham beetles are about 4-7 mm., but are a lovely metallic blue. They glint in the sunlight as they run over the surface of a dried corpse.

Red-legged Ham Beetle, Necrobia rufipes

Forensic entomology is the study of insects that infest dead bodies. Blow flies (family Calliphoridae) play the most prominent role in crime scene investigations because they can help ascertain the time of death. The life cycle of flies progresses in a predictable fashion, faster at higher temperatures, slower at cooler temperatures. By collecting adults, larvae, and pupae, a criminalist can determine at what time a body was first visited by ovipositing female flies.

Obviously, other insects play a critical role in decomposition as well, and beetles are chief among them. Those of you with strong stomachs may want to examine animal carcasses you come across, as the insects found there can usually be found nowhere else. Just remember to pack the hand sanitizer.