Signup to receive email updates

or follow our RSS feed


John Fulton

John Fulton
Former County Extension Director

Blog Archives

732 Total Posts

follow our RSS feed

Blog Banner

In The Backyard

Horticulture columns and tips done on a timely basis
Mature bagworms


Posted by John Fulton -

After some very severe infestations of bagworms the past few years, the calls have been coming in all year on the correct treatment times for bagworms this year.Year-in and year-out, the correct treatment time for bagworms is June 15. You can mark this date on your calendar for next year and be within a few days of the correct treatment time. With a very cool spring, a week later may be a possibility The idea is to have all the eggs hatched before treatment.

The next problem is what to use. The traditional standby has been Sevin, and the synthetic pryrethroids such as permethrin or bifenthrin, but the B.t. products such as Dipel and Thuricide have really taken their share of the market the past several years. The B.t. products have several good points including safety to mammals and toxicity to larger bagworms. Since they are bacteria that affect only the larvae of moths and butterflies, it does take a while for the bacteria to build up to the point where they can kill the bagworm. I won’t get into the discussion about Monarch butterflies lighting in the tree just after treatment. The latest research on the Monarchs shows their numbers are declining due to loss of food and habitat – in essence, less milkweed plants overall.

If you are in doubt about whether you have bagworms, check your trees and you can actually see the small bags as the larvae build them. They become very noticeable at about 1/16 of an inch long. Treat bagworms early, since larger ones are more difficult to control, but waiting a week this time of year will also make sure all eggs have hatched into a controllable stage.

Most people think that bagworms only affect evergreens. True, that is their preferred host group, but bagworms have a huge number of potential hosts. Through the years I have seen them on oak trees, grape vines, apples, and about any other growing thing you can think of.

Please share this article with your friends!
Share on Facebook Tweet on Twitter Pin on Pinterest