Q: I have a shallow pond (100′ x 100′) that occasionally goes dry in summer. I get lots of mosquitoes from it when it dries and leaves small puddles. Is there a way to control mosquitoes in this situation?

A: The chemical methoprene (click for sources) is labeled for use in your situation. It is an insect growth regulator that keeps mosquitoes from developing into adults. It can be used preemptively to control them, so you can apply it before the pond dries out.