A: That is a banded tussock moth caterpillar, and they can sting! These stinging hairs can cause a rash for those with sensitive skin. These caterpillars eat the leaves of many hardwood trees. To survive the winter, they use their hairs to spin a gray cocoon.

And if you’re seeing lots of black smudges on the concrete beneath some oak trees, that’s the mess from orangestriped oakworms. Adults begin to appear in early summer, and leaves on host trees will come to look skeletonized.

Bacillus thuringiensis (Bt) is an insecticide that can be used on both of these at their early stages, but in most cases, they won’t damage a plant enough to kill it.

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