There's a Moth in my Salad!

Entomophagy is the term for the intentional consumption of insects as food; but you would be surprised by how many insects turn up in foods we eat regularly. Two recent incidents reminded me that it is remarkable we don’t find more recognizable insects in our food, and why it shouldn’t bother us anyway.

I was having lunch with my wife and various friends from church at a chain restaurant on Sunday, April 6, when one member of our party discovered an intact moth, yes moth, amongst her salad greens. We were both eating the same salad, so I was a little more careful with succeeding bites. I took home the specimen and discovered it to be a member of the Noctuidae or Erebidae family. This wasn’t surprising since the caterpillars of many owlet moths are notorious crop pests, several of which are known as “cutworms.”

Yep, that's a moth

The prevalence of insects or insect parts is so commonplace and unavoidable in the harvesting, processing, storage, and shipping of food products that the Food and Drug Administration publishes an entire handbook on the subject of Food Defect Action Levels. The allowable number of insect parts, or even whole insects (collectively referred to by the unsavory term of “insect filth”), varies markedly according to each food product.

On the other end of the spectrum, we have situations whereby perfectly innocuous vegetable matter is interpreted by a restaurant patron as an insect. I received a sample of material obtained from a meal at another chain eatery. Previous casual observations of the “specimens” by other parties concluded they were either insects or the parts of one insect. My own examination revealed no segmentation, no differentiation of body parts, and therefore no insect(s). The resemblance is, arguably, startling, kind of like camouflage or mimicry in reverse.

Nope, not bugs

The blackened, fibrous roots or stems masquerading as bugs were, of course, a cosmetic issue, just as an actual insect would be. With few, minor exceptions, insects in your meal pose no health threat whatsoever. We are simply accustomed to pristine produce, unblemished fruits and vegetables. Our crops are sprayed will all manner of insecticides, waxes, dyes, and other coatings to give us this standard. It is akin to airbrushing and “Photoshopping” images of models to present us with an unrealistic standard of human beauty.

I will still find it gross to come upon an insect in my salad, or a fly in my soup, but it won’t bother me beyond that. I was quite impressed with the nonchalant reaction of our friend, who simply removed the moth and went on eating….without calling a lawyer, even.

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.

Mourning Cloak

I have neglected butterflies on this blog for the most part, as there are plenty of other blogs about them, books and websites, too. Plus, let’s face it: they are easy to love. My general mission is to stir a passion for other insects and invertebrates. That said, at this time of year along the Front Range of Colorado, certain butterflies are the most obvious of insects. The Mourning Cloak, Nymphalis antiopa, is also admirable for its sheer durability.

This butterfly is one of the “tortoiseshell” butterflies, a subgroup of the family Nymphalidae, collectively known as “brushfoots.” Look at any nymphalid and it looks like the insect has only four legs instead of the customary six. The front legs are greatly reduced in size and drawn up close to the head, where they function more like extra mouthparts than legs. The female butterfly scratches leaves with those tiny legs, causing the plant to produce volatile compounds that the butterfly analyzes to make sure it is a proper host plant on which to lay her eggs.

Tortoiseshell butterflies overwinter as adult insects, crawling into crevices and cavities in logs, stumps, and other protected spots. A warm winter’s day will see them taking wing, before going back into hiding until early spring.

Once a Mourning Cloak emerges from hibernation, it seeks sustenance to fuel its flights. A favorite source of nourishment is sap oozing from wounded trees. Indeed, a sap flux can quickly become a mecca for these butterflies, as evidenced in the short video below. They are amazingly tolerant of each other’s company considering their usual behavior.

Male tortoiseshell butterflies are highly territorial, each one staking out a patch of real estate that it defends vigorously from other males, and even from other species. I say many a battle between a male Mourning Cloak and a male Hoary Comma on April 11, the day I shot most of these images along a riparian trail near the Bear Creek Nature Center in Colorado Springs. The insects would often literally bang into each other during their aerial dogfights.

While males quickly become tattered and exhausted, females, once mated, set about to find suitable host plants on which to lay eggs. You will find the Mourning Cloak to be most abundant in willow thickets, as Salix spp. are the favored hosts. Caterpillars will also feed on elm, birch, poplar, hackberry, rose, mulberry, and other trees and shrubs to a lesser degree.

Large masses of eggs, typically 100-200, are laid by the female, the ova encircling a branch or twig. The caterpillars pass through five instars (an instar is the interval between molts), eventually topping out at about 5 centimeters (two inches) in length. Black with white speckles and maroon spots, the larvae are studded with spikes.

They occur in large groups, so when you find one you will usually find several more nearby. During their younger instars they share a loose, tent-like web for protection from predators and parasites.

By June or July another generation of Mourning Cloaks is on the wing. There may be two generations in the southern reaches of this butterfly’s range, but at higher elevations and latitudes there is but one generation produced each year, fresh adults emerging in late August or early September.

The Mourning Cloak is holarctic, meaning it is found throughout the northern hemisphere. In Britain it is known as the “Camberwell Beauty.” Here in North America, it ranges from Alaska to Mexico, and the Pacific Coast to the Atlantic seaboard.

Few insects live as long as a Mourning Cloak in the adult stage. On average, they survive 10-11 months, though much of that is sequestered in a hibernaculum. They are always a welcome sight, and a true harbinger of spring if ever there was one.

Sources: Brock, Jim P. and Kenn Kaufman. 2003. Kaufman Field Guide to Butterflies of North America. Boston: Houghton Mifflin Co. 384 pp.
Ferris, Clifford D. and F. Martin Brown. 1980. Butterflies of the Rocky Mountain States. Norman: University of Oklahoma Press. 442 pp.
Pyle, Robert M. 2002. The Butterflies of Cascadia. Seattle: Seattle Audubon Society. 420 pp.

Beetles from Bones

This past Wednesday, April 9, I went exploring near my home to see what insects are out and about here in Colorado Springs this spring. In my wanderings I stumbled upon a few bones of some large mammal, providing an opportunity to find insects specific to carrion.

I am not terribly keen on handling carcasses, but these leg bones were mostly dry. The ligaments were still intact on one leg, but flies had long lost interest in these remains. Still, it takes little to attract ants, and some kinds of beetles. I managed to find three species large enough for photos, plus a couple very tiny rove beetles (family Staphylinidae) that quickly vanished when I turned over the bones.

The first insect I saw was, oddly, a Small Milkweed Bug, Lygaeus kalmia. Many normally herbivorous Hemiptera are opportunistic scavengers, though, so perhaps the appearance of this insect should not have been terribly surprising. The second insect was one I expected, and present in fair numbers considering the relative size of the carcass: Common Carrion Beetles, Dermestes marmoratus.

Dermestid beetle and Small Milkweed Bug

Dermestids are so efficient at scouring the last vestiges of flesh from bone that natural history museums employ colonies of the beetles to clean skeletons. This particular species, a relative of that indoor pantry pest the Larder Beetle, is a handsome insect measuring 10-13 millimeters. The silvery-gray scales on its otherwise black body make it look quite dapper considering the situations it frequents. D. marmoratus is found from southern California through the southwest, southern Rocky Mountains, and Great Plains states.

Dermestes marmoratus

The most spectacular specimen uncovered was a Northern Carrion Beetle, Thanatophilus lapponicus, also known as the Silky Carrion Beetle. It looks superficially like a giant dermestid, 8-15 millimeters in length, but it belongs to an entirely different family, the Silphidae. This species is holarctic, meaning it ranges across the entire northern hemisphere. In North America it is found in Alaska, Canada, and the northern tier of states in the U.S., plus the Pacific states to Baja, Mexico, and the Rocky Mountain states. The adult beetles have been found from March to October. Perhaps its hairy body helps to insulate it against cooler temperatures.

Thanatophilus lapponicus

The last beetle species I collected was a type of sap-feeding beetle in the family Nitidulidae. At only 3-5 millimeters, Nitidula ziczac is difficult to spot, let alone get a clear image of. Despite their name, sap-feeding beetles are highly diverse in their appetites. Some species are found in abundance inside yucca flowers, for example. N. ziczac is a well-known associate of carrion, found in North America mostly from the Great Plains westward, as near as I can tell from various references.

Nitidula ziczac

What truly amazes me about carrion-inhabiting insects is how they manage to locate such a scarce resource. They need the energy to fly to far-flung bodies, at just the right time. Certainly their olfactory powers are light years ahead of us humans (I detected absolutely no odor from these particular bones), and tuned specifically to aromatic compounds liberated during decomposition. However they do it, thank goodness they do, or we would be forever tripping over dead animals, before becoming deathly ill ourselves.

Source: Evans, Arthur V. and James N. Hogue. 2006. Field Guide to Beetles of California. Berkeley: University of California Press. 336 pp.