Bag Worm Control

Bag worm damage on evergreen branches

Its that time of year again when bagworms could appear and unfortunately, they damage plants. Bagworms prefer juniper, arborvitae, spruce, pine, and cedar but also attack deciduous trees.  The bags hold over 300 eggs in the cocoon and disperse in late spring by “ballooning” or crawling. The caterpillars feed for up to six weeks. Larvae strip evergreens of their needles and devour whole leaves of susceptible deciduous species, leaving only the larger veins. Large infestations of the caterpillars can defoliate your evergreen living fence. Heavy infestations over several years, coupled with other stresses, can lead to plant death. 

In Maryland, I use the 4th of July as a reminder date to look look for them.  They are very small then and are easy to kill with organics such as Bt or dipel, and insecticidal soaps. The picture is of how small they are when they first get started eating the leaves of your plants. This year, due to the 31 degree nights in our region in early May, the hatching seems to be about 2 weeks late. There is no pre-spraying early for them, as they are not out yet and the winds may not blow any female moths onto your evergreens. If only a few small trees or shrubs are infested, handpicking and destroying the attached bags may provide satisfactory control, but must be done before the eggs hatch, it can be a tedious project if you have a lot of them. Once the bagworms become larger, they develop two stomachs, then they are very resistant to organic control products. On large bagworms, traditional pesticides must be used. Always follow the label, rate and safety instructions. We are Pryor’s Nursery only use organic methods to control any bagworms, but luckily we have not any infestations in many year.

#Bagworm #evergreens #livingfence

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