Dormant oil spray and bagworms

Asked September 8, 2019, 9:33 AM EDT

Is dormant oil spray affective in eradicating bagworms and if so what recommendations for its use.

Frederick County Maryland

1 Response

Horticultural oil will not kill bagworms. In fact, it is too late to spray for bagworms this season. They are not feeding at this time and are in the process or getting ready to reproduce. At this time of the year pick off and destroy the bags if you can reach them.
The next opportunity to spray for them is in late May through early July using a biological control called Bacillus thuringiensis (Bt). There are many brands on the market.
Please see the following information found on our website,
https://extension.umd.edu/hgic/topics/bagworms-trees-and-shrubs
And just in case you are referring to fall webworm,
https://marylandgrows.umd.edu/2019/08/12/whats-eating-my-tree-bagworms-or-webworms/

Deb