By Andy Mills
Since the beginning of time (at least my time) we’ve been battling bagworms. Usually, these inconspicuous insects go unnoticed for a few years until their damage is obvious. By then, their destruction may be irreversible.
Bagworms begin their life cycle as an egg laid in the fall in their bag. Usually in late May and early June the egg hatches and the tiny larvae starts its destruction. As it eats and moves it secretes silk to form a bag of tiny debris it collects in the tree or shrub it is in. By the end of the summer it has formed a 1 ½ to 2 inch bag all around its body. Once the caterpillar matures it pupates. Males leave their bag as a moth in search of females. Females do not fully form wings and remain in their bags to attract males. After mating an egg is laid and remains in the bag all winter before hatching the following spring/summer. Even though the caterpillars are tiny now and are hard to see because of the camouflaging of their bag, they are very easily killed with an insecticide at this stage. Organic insecticides containing Bt or Sinosad are safe products that are very effective now. As we get later into July the larger bagworms are more difficult to control so insecticides containing bifenthrin, cabarye, or cyflurin will have to be used. If you miss the spraying windows the bags can simply be removed this fall and winter before hatching next spring. Keep in mind the later we wait for control the more damage will occur. The caterpillars defoliates and causes browning in several types of trees and shrubs including arborvitae, juniper, pine, red cedar, spruce, and locust trees.
As like most plants we grow in the garden and landscape, a pest is always wanting to infest them. Therefore, monitoring and acting at first signs of a problem usually is the key to a healthy plant. Damage caused by bagworms is no different. Controlling this pest now is easy and will help the health of your landscape plants in the future. Therefore, take care of the problem now so you’re not paying to replace plants later.
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