Tuesday, May 29, 2007

Host Plants

I found this caterpillar on the Ouachita Trail at Walter B. Jacobs Memorial Nature Park. I was inspecting Paw Paw (Asimina triloba) leaves for Zebra Swallowtail caterpillars.

I have read that Zebra Swallowtail caterpillars eat only leaves of Asimina species. I have read that Paw Paw Sphinx caterpillars eat only Asimina species. I have read that there is this pyralid moth with no common name (Omphalocera munroei) that eats Paw Paw leaves so voraciously that it defoliates the trees in the middle of the summer, stimulating the trees to grow new leaves, providing the last generation of zebra swallowtail caterpillars with an unusually abundant food supply, and thus is responsible for increasing the population of adult Zebra Swallowtail butterflies that fly in the fall.

I discovered a folded Paw Paw leaf, and pried it open to peek inside, curious to see if I had found a Zebra Swallowtail caterpillar, or a Paw Paw Sphinx caterpillar, or the never-seen-by-me O. munroei. I found this. It's a Spicebush Swallowtail caterpillar. As you might guess Spicebush Swallowtail caterpillars eat Spicebush (Lindera benzoin). They are also known to eat Sassafras. Some sources say they will eat Sweet bay, Swamp bay, laurels. Caterpillars in the Field and Garden say the Spicebush Swallowtail caterpillar "lives in folded leaf shelters on the host." ON THE HOST.

That's a Paw Paw leaf I'm holding. So did I just find another host for the Spicebush Swallowtail?

[By the way, the Zebra Swallowtail caterpillars seem to stick to the underside of the Paw Paw leaves. I have discovered that curled Paw Paw leaves most often conceal little jumping spiders.]