What's on Dat Scat?

My last post addressed what kinds of insects can be found in dung, but today I want to show you what can be found on animal poop. While blow flies, family Calliphoridae, are often overwhelmingly abundant on fresh manure, you'd be surprised what else comes in for a taste.

Acmon Blue and Reakirt's Blue enjoying some refreshing scat with broad-headed bugs

Would you believe many butterflies will visit scat? Last year I happened upon this scene on a concrete nature trail in a popular park here in Colorado Springs. There were two species of gossamer-winged butterflies imbibing from some kind of predator poo. The ones with the orange bands on both the front wings and hind wings are Melissa Blues. The one with orange on the hind wing only is an Acmon Blue. The other one, without orange bands, is a Reakirt's Blue.

Melissa Blue joins Reakirt's Blue and broad-headed bugs

Males of many butterflies require mineral supplements that they can pass along to females during mating. Dung is one such mineral-rich resource.

Some butterflies feed mostly on dung, or carrion, and hardly ever visit flowers. Among them are the satyrs like this Northern Pearly-eye that was visiting dung on a bike trail in a suburb of Chicago, Illinois.

Northern Pearly-eye butterfly

The Red-spotted Purple is also notorious for preferring dung and corpses for nourishment, though one usually sees the territorial males perching on the ground or up on leaves in the canopy along stream or river corridors, or forest edges.

Red-spotted Purple butterfly

Other surprising visitors to scat are true bugs that normally feed on ripening seeds or other plant material. Finding so many broad-headed bugs, family Alydidae, sharing the poo-pile with the butterflies was quite surprising. There are at least two species here: Megalotomus quinquespinosus is the brown one, known as the "Lupine Bug." The other, smaller and blacker, is a species in the genus Alydus.

Male Golden Dung Fly

Different kind of excrement seems to attract different kinds of insects, at least to a degree. Fresh cow and horse dung is a favorite breeding ground for dung flies in the family Scathophagidae. The males stake out pats of poo and defend them from other males, while also intercepting females receptive to mating. The female lays her eggs in the manure and the larvae that hatch feed and develop there. You can easily recognize males of the Golden Dung Fly, Scathophaga stercoraria, but their fuzzy, bright golden appearance.

Various blow flies on what is probably bear scat

The blow flies (Calliphoridae) come in two basic varieties: "greenbottles" that are wholly metallic green, mostly in the genus Lucilia, and "bluebottes" that are usually larger, and gray with a metallic blue abdomen. Most of the common bluebottles are in the genus Calliphora. There is also the Black Blow Fly, Phormia regina, that is black or deep metallic blue-black. All can be present at dung.

Black scavenger fly

Tiny and wasp-waisted, black scavenger flies in the family Sepsidae are not easy to see immediately given their size, but their behavior is unmistakable: they walk around "rowing" their wings as if they needed the extra propulsion to get around.

Flesh flies of the family Sarcophagidae are gray with black "pinstripes" on the thorax, and usually red eyes and a red "tail." They are about the size of the blow flies, though some are smaller. The females "larviposit." That is, they lay tiny maggots in dung or carrion, rather than laying eggs. Bypassing the egg stage gives them a head start in exploiting the food resource.

A mating pair of flesh flies

Dung-watching is probably not going to become the next big thing in the world of naturalists, but if you can get over the "yuck factor," you might find some interesting creatures among the clean-up crew. Just make sure you are up wind.

What's in Dat Scat?

Sometimes you have to literally get down and dirty to find interesting insects. Poking into animal dung, affectionately known as "scat," is a pretty smelly, gross business, but it can yield a diversity of insect life you are unlikely to see otherwise. A case in point came on April 13 when I visited the Bluestem Prairie Open Space along the edge of Johnson Reservoir just southeast of Colorado Springs.

Two half-buried Trox sp. and one red and black dung beetle, Aphodius fimetarius under coyote scat.

While dogs are not permitted in the area, I suspect the locals probably bring them in anyway, judging by the tracks and the scat I come across. Still, the overwhelmingly most common canines are coyotes, and their dung invariably contains lots of fur from their prey. This makes their excrement attractive to beetles more commonly found on carrion and mummified carcasses.

Hide beetle, Trox sp., on coyote scat, facing left

Hide beetles in the family Trogidae normally visit the dried-out remains of an animal body when little is left but skin and bones. Indeed, that is what they eat as adults and larvae, along with feathers, fur, and connective tissue. Apparently coyote dung is the next best thing to a dead body. I found a total of three Trox sp. on just one piece of manure. These beetles are almost invariably caked in gunk so as to be nearly unrecognizable as insects, or animals of any sort, really. When disturbed they go voluntarily comatose, so convincingly that I have given them up for dead, stiff specimens. I've been startled by having them re-animate in a vial or cup after several minutes.

Fully active Trox sp.

Another surprise on this chunk of poop was a skin beetle, Dermestes fasciatus or D. marmoratus, I am not sure which. Again, these beetles are usually much more common on carcasses in advanced stages of decomposition, including wet bones.

Skin beetle, probably Dermestes marmoratus

There were, however, some honest-to-goodness dung beetles in another piece of coyote scat that was a little....fresher, if one can apply that term to anything that doesn't smell the part. Aphodius fimetarius is a little red and black dung beetle that was introduced to North America from Europe probably a century or more ago. It is now widespread and common here, usually in cow pats. The larvae live and feed in the manure, then dig into the soil beneath it to pupate. There is probably one generation per year.

"Tumblebug," Canthon simplex, unfortunately lying trampled on a trail

The other dung beetle I found was one of the dung-rollers or "tumblebugs" as they are affectionately called. This species, Canthon simplex, is relatively tiny, adults measuring only 7-8 millimeters. The adults tear off a pea-sized chunk of poo and roll it into a ball, either females alone or in pairs with males. Rolling the ball away minimizes conflict with other dung beetles. Once a suitable site is located, the female buries the "brood ball" and lays a single egg inside. The grub that hatches feeds inside, eventually pupating within the now hollow sphere.

"Tumblebug," Canthon simplex

While I was looking for the dung beetles, a very small rove beetle, family Staphylinidae, raced up a grassblade and flew off before I had a chance to secure it. Rove beetles are predators of other insects, and many species visit dung and carrion to feed on fly maggots. Rove beetles are slender, almost serpentine, with shortened wing covers (elytra), and so may be mistaken for earwigs at first glance. Staphylinids are so diverse that identifying them is next to impossible for anyone but an expert; and it also frequently involves detailed examination of the male's genitalia.

Typical rove beetle, family Staphylinidae

Maybe you are not "into" dung fauna, at least not if it requires pawing through it with or without gloves and/or various instruments. Ok, no one can blame you; but before you dismiss the power of poo altogether, consider my upcoming post "What's on dat scat?" You will be surprised all over again.

Source: Ratcliffe, Brett C. 1991. "The Scarab Beetles of Nebraska," Bull Univ Nebr State Mus. Vol. 12: 333 pp.