BAGWORMS

Two insects are commonly called bagworms. The large tent forming caterpillars or webworms which are in actuality tent caterpillars, and the small bag forming insects known to plauge junipers and cedars, called bagworms.

Bagworms are caterpillars that make distinctive cone-shaped bags on a variety of trees and shrubs. The bags are formed from the plant material the insect is feeding on. While bagworms attack both deciduous trees and evergreens, they are most damaging to juniper, arborvitea, and cedar. Unless the plant is small or stressed to begin with, it usually takes a couple of years infestation of bagworms to completely strip a plant of its foliage and eventually cause it's death. Of course, large populations of the pest can accomplish this feat faster. Rarely do people notice the damage until it is past the time when sprays are effective and the damage is done for that year.

Bagworms are the caterpillar stage of a moth that is rarely seen. Only the males develop into typical moths capable of flight. The adult female is grub-like and remains inside the bag until just before she dies. Bagworms overwinter as eggs within bags fastened to twigs. Eggs hatch in May and early June. Almost immediately after hatching, caterpillars begin to spin tiny protective cases or "bags" around themselves. The bags are constructed of silk and needle fragments or leaaves. As the bagworm grows, leaf fragments are added to the bags which often grow to 2 inches in length by the end of summer. The bags protect the caterpillar from predators and insecticides. Adult males emerge from the bags in September as small black, clear winged moths, and fly around locating a female to mate with through the females bag entrance. The females are wingless and never leave the bag. The females can produce 500 to 1,000 eggs, after mating, which are deposited inside their bag. The female then dies, never leaving the bag. At this stage, spraying is ineffective. Hand pick and destroy the bags before next spring to prevent reinfestation.

If you are having a continual problem with bagworms, it may be necessary for you to begin spraying weekly from May through mid June with Dipel, Thuricide, or Sevin to attack the small larvae before they have a chance to make their bags.