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Sunday, August 8, 2010

The Ailanthus Webworm Moth

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.

How convenient!

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. 

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14 comments:

  1. These are very pretty moths. I thought it was some kind of beetle until I found a picture of it with an id.

    stephaniesuesansmith@gmail.com
    http://stephaniesuesansmith.com/ermine-moth-or-ailanthus-webworm-moth-atteva-punctella/

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  2. Stephanie,

    The first time I saw one I thought it was a beetle too.

    Julie

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  3. This comment has been removed by a blog administrator.

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    1. Jennie -- I pushed the wrong button and deleted your comment by accident! Oh no! (Jennie wrote that she found an ailanthus moth in her kitchen in suburban New Jersey and thought it was a beautiful beetle.)

      I am glad you found one and glad you found my blog about it.

      So sorry for clicking the wrong button!

      ;-) Julie

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    2. I am Jennie from Ohio and I too found one in my kitchen and thought it was a beetle. Very ironic!

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    3. Totally understandable because they have a beetle-like look -- at least superficially. Pretty, too, right?

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  4. I always find them on my eggplants. But they don't seem to damage them.

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  5. I just found one in my kitchen! I was going to kill it until I really looked and saw how pretty it was!

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    1. Good thing you stopped to look! Must be good luck to find one of these lovely things in your kitchen. I regularly catch and relocate insect intruders. Julie

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  6. I found one of these beautiful creatures outside my front door a couple of days ago. I was pretty shocked to find out that it was a moth. Two questions, if you don't mind: 1) Are there other varieties of moths that look so un-mothlike? and 2) In all the photos I've seen, only four legs are visible. Are the other two tucked under the wings? And, if so, are they visible when the wings are open? Thank you!

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    1. Hi Robin -- There are about 160,000 known species of moths in the world. I'll bet there are lots that don't look like typical moths. Just off the top of my head I suggest you google plume moth and hummingbird moth. You are right about that third pair of legs not showing up in many poses. Google images and you will see them in a few. As for showing when the wings are open, I don't think I have ever seen an ailanthus webworm moth open its wings except when flying. They don't typically spread them while perched. Lucky you to find one. Best, Julie

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  7. I found one outside of my apartment door in Brooklyn! It was there for a few days and today I thought perhaps I should investigate it. It's beautiful! I guess I will collect him and bring him to the park to set him free.

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    1. Good for you. They are so pretty! I am always happy to see them.

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