Thursday, June 12, 2014

Two caterpillars: a question of numbers

Everywhere we go, these days, we find more caterpillars. Most match one of these two:

Silver-spotted Tiger moth, Lophocampa argentata, found climbing our wall

I couldn't identify this right away, and planned to send it in to BugGuide, but I did my homework first; no sense giving them more work than I need to.

Limiting my search to immature moths, which includes eggs and chrysalises, I found 26,875 photos in the image file on BugGuide. Too many!

I switched to butterflies. Not because they were more likely, but there were only 4,375 photos of immatures. I looked through them all. No match. Back, reluctantly, to the moths.

We see Orange Underwings around here most years. And there were only 175 photos of immatures. But, sadly, not these guys.

I backed up the chain, to the Noctouidea, the night-flying moths. Only 14,175 photos to scan. And I think I've found my target, in the Tiger Moth category (4,150 immatures). And to confirm, I've seen an adult or two around here.

Unidentified caterpillar, at Elgin Heritage Park.

For this one, I started looking in the Tiger Moths. And it seemed that I might be on the right track, until, about 1500 photos in, I found a few similar ones that the experts were not sure of.

That's a good enough excuse for me to quit; I'm sending this one in.


  1. I'm glad you have plenty of caterpillars Susannah... I haven't seen one this year. Maybe I'm not looking hard enough but by an odd coincidence for the first time in ten years I haven't had birds nesting in the garden :(

  2. So, either the birds ate all the caterpillars or even the eggs, and left because there was nothing left to eat, or they didn't show up at all because you had no caterpillars. Or something else entirely is going on.

    It's worrisome when something that always happens, doesn't. A couple of years ago, we had a summer with almost no spiders. This year, some of them are back, but it's a different mix of species.

    We toss around ideas like temperature change, pollution, birds moving their range north, poisons (insecticide, weed killers, etc.), or just everyday randomness. But we just don't know.

    As you say, :(


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