Male Gypsy Moth

2015 December 19

I found this moth near our porch light on August 4, 2015.

I was struck by how “bat-like” his antennae were.

The way that they are dished forwards, he can probably sense not just that there is a female around, but exactly what direction her scent is coming from.

The backs of the antennae don’t look like they have as much roughness, so they are probably a lot less sensitive to smells coming from behind. It is also possible that this shape might make them more sensitive to sound, which would be useful for dodging bats.

So, I thought this was kind of an interesting-looking moth, and used the search term “bat-eared moth” to rummage around, until I found out what it was . . .

. . . a male Gypsy Moth, Lymantria dispar[1]

I posted about these before, back in 2011, when I raised a caterpillar up to adulthood. So you might think that I should have recognized this, right? Well, as it turns out, the reason I didn’t recognize it is because last time I had a female. Here she is:

As you can see, this is a really dimorphic species, the males look very little like the females. The females are basically just egg machines that are too heavy to fly. So the males are the ones that have to do all the flying, seeking out the females wherever they may be.

As I said in the previous posting about Gypsy moths, they are a serious invasive pest that can defoliate entire forests. So far we haven’t seen them in huge numbers, possibly because their primary predator (the deer mouse) is keeping them in check. But if something happens to the deer mouse population, we could have a problem here.

[1] Whenever I see the name Lymantria dispar, the second part always makes me think “despair”. Which is kind of an appropriate emotion to feel when confronted with gypsy moths.

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