A spindly little Wafer-ash, Ptelea trifoliata, springs from the ground, its interesting leaves marred by an unsightly bird dropping. But wait! We better look again...
No one does the bird dropping masquerade better than the caterpillar of the Giant Swallowtail. If there was an Oscar for Best Actor in Fecal Disguise, this would be our winner. These cats are big ones, too, at least when the caterpillar is in its last instar, or growth stage, as is the one pictured in these photos. I was fortunate enough to encounter this Giant Swallowtail caterpillar recently in Adams County, Ohio.
If the physical appearance of these long horns isn't enough, the chemical secretions that they are coated in might do the job. To me, the osmeterial secretions smell rather foul. I was about three or four feet from the caterpillar when I made the photo above, and in no time my olfactory senses were assailed by a distinctly unpleasant odor. I can't imagine that the osmeteria and its associated chemicals hold any charm for birds, spiders, mantids or any other creatures that might threaten the larva.
Giant Swallowtail caterpillars feed on plants in the Citrus family (Rutaceae). In Ohio, that's only two species, the aforementioned Wafer-ash, and Prickly-ash, Zanthoxylum americanum. Neither are true ash, but are related to the orange. Some savvy nurseries that specialize in native plants offer at least the Wafer-ash (the Prickly-ash, true to its name, is quite thorny and less likely to be sold). Try planting some Wafer-ash on your property, and perhaps you can also grow these fantastic beasts.
Following are some Ohio nurseries that sell Wafer-ash:
Naturally Native Nursery (extra points for selling Prickly-ash!)