Wood boring insect? Please help!...?

Question

I live in Michigan and I have been noticing small piles of sawdust under the steps on my deck. I looked and they seem to contain a little black squishy thing, looks like a raisin. I'm thinking larva? and whatever is boring makes a perfectly round hole about the size of pinky fingernail on the bottom side of the step. I don't think it is termites and I don't see any live insects anywhere around the area. Any ideas??

Answer 1

guessing carpenter bees...they make a perfect 3 / 8 inch hole.  At night shoot any type of insecticide into the hole.  The usually attack unpainted lumber so make sure the underside of the lumber is also sealed or painted