Petunia Worms in Reused Pots: Soil vs. Butterfly Source

Identifying the "Worms"

Second-year worms on petunias in same pot/soil—likely caterpillars (butterfly/moth larvae), not soil-dwelling pests. Butterflies lay eggs on petunias annually; larvae hatch and feed. Soil reuse is irrelevant.

Safe, Targeted Control

Thuricide (Bacillus thuringiensis kurstaki)—biological insecticide:

• Only kills caterpillars (Lepidoptera).
• Safe for humans, pets, bees, beneficials.
• Spray foliage; caterpillars eat treated leaves, stop feeding, die.

Why Not Soil Treatment

Caterpillars don't overwinter in potting soil—they arrive as eggs on leaves. Discarding soil wastes money and doesn't prevent next year's butterflies.

Apply Thuricide at first sign of holes; repeat after rain. Petunias recover quickly.