Bagworm moths live in many types of trees. Their larvae crawl to plants nearby and spin a web that hangs from the trees they are feeding on. We’ve had several calls about what these bags are, what’s inside the bag and how to get rid of it.

The bag is full of worms that grow into large caterpillars which are more difficult to kill. Late May and June are the best time to spray an ingestible insecticide such as Bacillus thuringiensis (BT) or Spinosad on the plant while the worms are feeding.

Some prefer to remove the cocoon(s) and burn or drown the caterpillars and resort to spraying only when the infestation is too heavy. They can be cut by hand or removed with high-powered water.

By July or August it’s difficult to kill them by spraying insecticide because their cocoons are stronger. It is then necessary to remove the cocoon and destroy it, making sure to kill all caterpillars inside.

These caterpillars eat the foliage on the host plant and can cause large-scale defoliation. Bag worms, when found, should be destroyed using one of the methods above to protect your plant.