Q: We recently planted several deodar cedar trees. The other day I noticed a group of yellow caterpillars gleefully chewing the needles. What are they?
A: Though it’s really late to see them, I think you have red-headed pine sawfly larvae. They aren’t caterpillars. The sawfly is a wasp-like insect and the eggs may have come in with the trees. Since they are not caterpillars, products containing Bacillus thuringiensis won’t kill them. Spray the trees with any garden insecticide instead.