Monday, July 18, 2011

Two New Friends I’d Like You to Meet

Hi there! Sorry for the absence, but you know how it is—summer—gotta live it up while you can. We recently took a trip to Ohio, and before that was preparation, and after that was dealing with all the stuff that had piled up. You know.

Meanwhile, I’ve been working on another lengthy post. (BAD blogger! BAD! I should know by now that “no one reads long posts” and that I’m just wasting my time. At the very least, I should break it down into smaller chunks. Right? Because everyone’s got ADD these days. Right?)

Well, anyway. Sometimes you do things just for yourself.

Today, I have a few new friends to introduce to you. I suspect both fall into the category of “I’ve seen them, but we’ve never been formally introduced.”

New Friend Number 1

First, I’d like you to meet a little fly (a dipteran—a two-winged insect) that has been unusually prevalent in our yard this year.

The name is “picture-winged fly”; it’s called that because of the little black, orange, and white triangles and dots that appear on the wings. Delphinia picta is the proper name. My photos are only so-so; you can see better ones here at BugGuide.

Viewed from above, they’re rather triangular. They have a habit of moving their wings in a circular motion while they’re walking around—like they’re rowing a boat.

If you’ve seen them before, you probably haven’t paid much attention to them, because they don’t bite or sting, they don’t fly in your face, they don’t enter your house.

The m.o. of the picture-winged fly, as far as I can tell, is that they love compost and other decaying things. As larvae, that’s their home and their food. (They’re kind of like fruit flies, in this respect.) I think that’s why we’ve been seeing them a lot this year: They’re especially prevalent around our compost bin!

Well, they can have that rotting ol’ leaf stuff: “Knock yourselves out, little dudes.”

By the way, I think that’s a gas mask they’re wearing!

New Friend Number 2

This one has a rather strange story. First of all, rest assured that this little insect (no more than 3/4 of an inch long) is indeed a moth. A moth with narrow wings that fold straight down its back.

Unlike a lot of moths, this one has pretty colors and is active during the daytime.

The name is ailanthus webworm moth, or Atteva aurea. (In this case, the scientific name is easier to learn and say than the common name!) Here it is at BugGuide.

Does the name “ailanthus” ring a bell? Well, Ailanthus is the genus name of the tree-of-heaven, an oft-planted (and oftener-escaped) tree originally from China. Like geraniums, begonias, and forsythias, ailanthus’s genus name has become its common name as well.

So Ailanthus altissima, the so-called tree of heaven, is as hardy as all get-out. Tough as nails! (One reason they were planted in urban areas is that they can survive in rough neighborhoods! One of their common names is “ghetto palm”; another is “tree from hell”!) They’re an invasive exotic pest tree that easily out-competes our native trees—they’re bad news, and in North America they deserve extermination much, much more than, say, rattlesnakes and copperheads, who belong here.

The ailanthus webworm moth uses ailanthus as a host tree—lays its eggs on it, and the larvae (little silk-spinning caterpillars) gobble up the leaves.

So now you’re wondering if the ailanthus moth didn’t also come from China—perhaps as an experiment in biological control. But no! They are a native North American moth whose original favorite host trees are the tropical paradise trees (genus Simarouba).

Ailanthus webworm moths are originally native to the tropical Americas, where paradise trees grow, but now that they’ve found ailanthus trees to be delicious, too, they migrate north each spring—even into Canada—to take advantage of all the free food. (Unfortunately, they don’t seem to do much harm to the evil, invasive ailanthus trees. Poo!)

Apparently the ailanthus webworm moths cannot survive freezing winters, so you have to wonder what the point is to them breeding and laying eggs on ailanthus trees this far out of their survival range. It sounds like any eggs, larvae, pupae, or adults caught here in December would expire the way an orange tree would.

Hmm. Maybe the moth’s lifestyle is just as messed up by the presence of the invasive tree as all the trees and other interconnected, native organisms being displaced by it.

So the next time you see one of these pretty little ailanthus moths, think of its unknowing sacrifice up here in the cold northlands, and thank it for doing its best to help cramp the style of those invasive trees.

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