The worm is a soft brown caterpillar encased in a silken cocoon-like bag covered with bits of leaves from the host plant. Bagworms usually appear in late May or June, and feed on foliage. Eggs over-winter inside the bags, hatching in June into dark brown larvae that begin to feed and construct bags immediately. They pupate in early September. The winged males emerge as adults in a few days and fly to bags containing wingless females and mate.
Females then deposit their eggs in the cocoon where they over-winter.
This insect is much easier to control around the first of July when small and actively feeding. As they mature, they become more difficult to kill. In early stages, thorough spraying with Dipel, Isotox, Diazinon, or Sevin is recommended and will usually control this insect. Spraying with insecticides after September 1st will not control the pest and then one must manually pick off the old bags and destroy them. Follow the directions on the label as to mixing and then completely cover all parts of the plant to the point of spray run-off.