Ant Lion Adult

2008 July 19

Last year, I had an entry about ant lions, with pictures of the larval form (which digs pits in sandy soil and grabs unwary insects that stumble ino them). Well, here is the adult form, that S_ just caught for me out on the front porch:

She caught it pretty easily, because its front left wing was badly deformed, and all it could do was flutter about. It evidently didn’t inflate properly when it changed from the larval form.

Adult antlions can easily be mistaken for damselflies, which have similar body shapes, head shapes, and wings. The big giveaway is the antennae: antlions have medium-length antennae-

that end in a somewhat fattened hook-

while damselflies barely have any antennae at all. Antlions evidently aren’t as strong of fliers as damselflies, either, and when they flap their wings it makes kind of a soft, breathy noise, sort of like a moth.

I’m not sure what, if anything, the adults eat. They have pretty minimal mouthparts-

unlike the rather startling jaws of death that the larval form has-

so they may just be mating machines that emerge, mate, lay eggs, and then die of starvation.

I was a bit startled to see just how huge the adult was (almost two inches long) compared to the larva (about half an inch). They evidently are very flimsily constructed as adults, with a very low body density, so they are able to stretch their larval mass out to fill a lot of volume.

There are two ways that I’ve seen recommended to collect the adults: (1) set out a sticky trap near a light at night, or (2) find one of the larval pit traps, keep it as a pet, and catch the adult after it pupates. Catching a deformed one like this one during broad daylight was quite a stroke of luck.

Last year, we found ant lion larvae with pits in the yard in the spring, then they disappeared around July, and then they reappeared in August.  Since S_ caught this adult in July, it looks like the lifecycle of the local antlions goes something like: lay eggs in late July, grow up partway, and then overwinter as half-grown larvae. Finish growing in the spring, then pupate in late June/early July, emerging as adults to lay eggs in July.  Of course, this assumes there is just one generation a year.  We should probably raise one at some point to see just how long the local species lives.

2 Responses
  1. July 19, 2008

    Good photos. It’s a wonder it has survived the predators with a wing like that. I sometimes get them in my light trap of a night. In some cases at least, the adults feed on nectar and pollen.

  2. July 20, 2008

    It’s quite possible that it didn’t actually survive very long outside – S_ caught it less than four feet from a spot where we spotted ant lion pits last fall. I expect that it had emerged very close by where she caught it, possibly only an hour or two earlier. I let it go when I was done with it, but I don’t really expect that it survived.

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