|Ailanthus altissima, the tree-of-heaven.|
You may have seen this weedy looking tree growing in a vacant lot, or an alley, or in the space between sidewalk slabs. It thrives in cities and seems able to grow almost anywhere, even out of the sides of abandoned buildings. It has a strong smell that stays on your hand when you crush a leaf.
It's a Chinese native that was introduced to the United States in the 1700s. It became naturalized and can now be found growing wild all over the country. This is the famous tree that Betty Smith wrote about in "A Tree Grows in Brooklyn."
The ailanthus tree has its own moth, Atteva aurea, the ailanthus webworm moth. The moth holds its wings rolled and close around its body while resting, so it looks a little like a long beetle.
|Atteva aurea, the ailanthus webworm moth.|
Like many other insects, this one was named after the food it eats -- ailanthus leaves. The "webworm" part of the name refers to its lifestyle during the caterpillar stage. The "webworms" spin silk webs on ailanthus trees and live in groups while eating foliage, like more familiar tent caterpillars.
|Ailanthus webworms at home in their silk web.|
Like the ailanthus tree, the ailanthus webworm moth is an introduced species. Except for populations native to southern Florida, ailanthus webworm moths came from Central and South America, where they feed on a tree that is closely related to the tree-of-heaven.
The introduced ailanthus webworm moth switched its diet to the introduced ailanthus tree and they took off together across the country.
There is more information about urban insects in my book, Field Guide to Urban Wildlife, which will be published by Stackpole Books in spring 2011.