The Sphinx Moths lay eggs on tree and hatch out caterpillars (Catalpa Worms ) Never saw a nest just eaten leaves. They grow fast so keep a close watch cause once mature the worms leave. I pefer to use them fresh for bait. Catfish love those worms. I put them in plastic bags in the crisper drawer and the cool keeps them good for several days. The little woman hates it but sure good place to keep them. I plant the Umbrella Catalpa trees as they don't get real big like Northern or Southern Catalpa trees making harvesting worms easier.