Nature is to be found in her entirety nowhere more than in her smallest creatures.
~Pliny the Elder (Roman scholar)
When visiting Yellowstone, it is a great thing when you have a “three dog day”. That refers to a day where you are lucky enough to see the three primary species of canids found in the park – a Red Fox, a Coyote, and a Gray Wolf. Yesterday, in my yard, I had a different type of triple sighting, but I’m not quite sure what to call it. I am definitely in late summer mode, which means caterpillars on the brain, an annual disease that afflicts people like me and anyone else working the BugFest caterpillar tent. So, starting about now, anytime I take a walk outside, my eyes seem to be constantly scanning the vegetation for Lepidoptera larvae.
There have been large numbers of Eastern Tiger Swallowtail butterflies in the yard the past several weeks. This phenomenon occurs every few years when some unknown (to me anyway) set of environmental conditions are right – the flowers are crowded with bold yellow and black-striped butterflies. There are also a lot of black-colored swallowtails mixed in, representing a few common species – Spicebush Swallowtails, Black Swallowtails, and the occasional Pipevine Swallowtail. And there is one other – female Eastern Tiger Swallowtails can either be the familiar yellow color with black stripes, or they can be a darker morph, appearing black, or black with a hint of yellow.
So, with all this recent swallowtail activity, my first stop on the caterpillar hunt was a grouping of sapling Tulip Poplars, a primary host plant for Eastern Tiger Swallowtails. After scanning a few, I finally spotted a larvae on the surface of one of the large leaves, resting in a silk pad. This is typical behavior for this species. And, like most of its swallowtail family, the earlier instar larvae resemble bird poop. Guess it is a great strategy to avoid being eaten by foraging birds – look like something they have already eaten and processed. The larvae of this species will eventually turn all green (with small fake eye spots) as it molts and matures.
Continuing my stroll, I caught the unmistakable black and yellow pattern of another member of the swallowtail group (family Papilionidae) tucked under some Parsley leaves. Black Swallowtail larvae also start out as bird poop mimics, but this one was in its last instar and had outgrown that unsavory likeness.
The next stop was a semi-bog garden. There are chances here for two additional species of swallowtail larvae – Spicebush Swallowtails on the Spicebush, and Zebra Swallowtails on the Pawpaw. There were several folded leaves on the Spicebush, the telltale sign of caterpillar activity.
I carefully unfolded one leaf and found a comical-looking Spicebush Swallowtail caterpillar. These little guys are one of my favorites, with their large, detailed fake eye spots giving them a bit more personality than most larvae. All stages of the larvae of this species spin silk across a leaf causing the leaf to gradually fold over as the silk dries and contracts.
It makes a good hideout and probably provides some protection from the many predators out there, especially the hungry birds and paper wasps (wasps cut up caterpillars and feed them to their larvae in the nest). But it also makes them easy to find for us caterpillarophiles.
There were a lot of folded leaves on the plants, especially one near the house I had trimmed that had re-sprouted. I think these fresh leaves are perhaps more palatable for the larvae and therefore more sought out by egg-laying female butterflies. One sprouting plant had what appeared to be all stages of development of the Spicebush Swallowtail larvae (another bird poop mimic in its first three instars).
I tried in vain to find a Zebra Swallowtail caterpillar on the Pawpaw (its host plant), but I have always found them to be one of the more difficult larvae to locate. But, three swallowtail species in one afternoon – not bad. A three cat day? Three cat-tail day? Whatever it should be called, it is a good thing.