Big Ugly Worm
Hi. We have been enjoying your site very much since we discovered it a few days ago. Now we have found a weird ugly bug we would like to have identified. We live in northeastern PA. Our area is heavily woodedbut we are not near water. This THING was seen “inching” along on the concrete pad by my pigeon lofts. It moves by bending itself up into a bow shape, then reaching out with the front. It’s like an inchworm, only much bigger and uglier. It has 4 caterpiller-like feet (my son says they are pseudopods) on the back end, and about 8 claw-like feet on the front. It SCARED us! What is it?
Thank you,
Sue and David

Hi Sue and David,
You can stop being scared of your Spanworm or Inchworm, one of the Geometrid Caterpillars. They are very difficult to positively identify. Our best guess is the Oak Besma, Besma quercivoraria, which eats a wide variety of forest trees besides oaks including conifers. There are conspicuous wartlike swellings that help it to mimic a twig that has had the leaves drop off, especially when the caterpillar rests by streching straight out at an oblique angle. Here is a page full of Geometrid Caterpillars from the Caterpillars of Eastern Forests website.

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