Home > Great Big Greenhouse Blog > June 2017 > IN THE GARDEN with DOUG - IT'S TIME TO SPRAY FOR BAGWORMS


Do you know what a bagworm is? Most people don’t realize they have a problem on their evergreens until later this fall when they see these teardrop shaped brown bags hanging from the branches and they realize how weak and thin their evergreens appear. Bagworms can be a serious problem around Richmond but, when caught early, they are relatively easy to control.

Bagworms are beginning to hatch from their protective cocoons. Bagworm control starts with understanding the worm itself. These worms will use over 100 different plants as their food.  Some of their more popular plants to eat are Arborvitae, Leyland Cypress, junipers, Eastern Redcedar, pine, and others. Treatment for bagworms can only start at certain times during their lifecycle. In our area, treatment should start now through mid-July.

Here is a quick synopsis of the lifecycle: The bagworm overwinters in this brown, teardrop shaped bag that was put there by last year’s females. They hatch out in May and June and crawl out of their sacks, eating the plants until late summer. Then they start constructing a bag made up of silk and plant parts around their own bottom and will eventually bury themselves inside of it for four more weeks as pupae. In the fall, the female will release sex hormones that attract the males. The males leave their sacks and go to the female bags where she can lay 500 + eggs after mating. The best control is during this crawling, eating stage BEFORE they construct this protective bag. AND, FOR US, THIS IS NOW!!

One may want to consider the biological insecticide Bacillus thuringiensis (BT).  The Bonide product called THURICIDE is a good BT product. Thuricide, when applied properly, is good for controlling different moth larvae (caterpillars), and leaf eating worms. As always, you want to familiarize yourself with the product by reading the label thoroughly. And, the time of day to spray is very important in order not to harm some of our beneficial insects. Spraying in the evening is suggested. Please keep in mind that BT products have short residual activity and will require more than one application for control.

You may ask yourself is there any organic control for bagworms? You can just leave the whole thing up to the birds.  When it comes to how to organically kill bagworm larvae, the birds do it best by going around the tree and eating the worms. This, however, is no way to really control the bagworms. In the fall, you can actually go around and pick the sacks off the trees yourself. This is a good way to organically eliminate the worms, but it can be tedious project if you have a lot of them or if they are high up in the arborvitaes and cedars.
Treatment for bagworms is not too difficult so long as you approach this task at the right time in the bagworm life cycle. Remember that June is best, as soon as they are hatching.
Posted: 6/21/2017 by Doug Hensel | with 0 comment(s)
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