Use BT (Bacillus thuringiensis israelensis) that they have for mosquitos. It is market under several names to control mosquitos in stagnant water. The most common brand name is "Mosquito Dunks," available at Wal-mart, Lowes, Home Depot, and you garden supply store. Just take the dunks, break them up into smaller parts and sprinkle the top of the potted plants. This is a bacteria that will only infect insects and is totally safe to your chameleon.