Bagworms have been hatching for the past week or so. I found the first hatchlings at a hot site on the south side of an NCSU building. First instar bagworms quickly make tiny bags and begin feeding. The bags are held upright and look like little ice-cream cones until later instars when large bags hang below branches. You can scout for bagworms any time of year because the bags ‘hang’ around for a long time. Bagworms are relatively sedentary during their lifetime, most often remaining on the same tree until they pupate. Adult females are wingless and never leave the tree, while male bagworms pupate and develop into a small brown moth. Females lay eggs in the bags each fall that hatch in late spring (now!). So you know if you have bags you have eggs and thus new bagworms.
Heavy bagworm infestation like the one in this picture can defoliate evergreen foundation plants and privacy hedges making them not-so-private anymore. One of the most effective, yet time consuming methods of treatment are hand-picking or cutting the female pupae bags off of the branches. Since this may sometimes be impractical or impossible, there are other methods of treatment to be considered. There are chemical control options available that should be applied during the early instar stages of the caterpillars since these are easier to kill and have not yet defoliated your plant. As with many other pest insects, bagworms are susceptible to predation from parasitoids and birds which can also assist in their control.
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