HUNTINGTON, W.Va. (WSAZ) -- Bag worm is a good description of an insect that just loves many evergreens. They get their name from their construction ability to make a house out of dead material in which to live in and looks like a sack Santa would sling over his shoulders. When they are mature, that in fact is what you see hanging on evergreens like tree ornaments at Christmas time. As a matter of fact, when their house gets that big, you have lost the war with bag worms.
In the development of any insect, there is one or more times in their development that they can be eliminated depending on what pest control you use. However, when the bag gets 1-2 inches long, the larvae living inside is way too mature for insecticides to control. Furthermore, by the time they get that large, they have probably eaten half your evergreen.
To control bag worms, you have to start early with a control. Take a look at your calendar, when June 15 comes around, its time to spray especially if you have been bothered in past years. Around June 15, they have hatched from an egg and just started on a full course meal of your plants. It's this time that a chemical spray will certainly be effective. Any later date will diminish your control chances.
There are non chemical products that contain BT like Dipel and Chemical sprays like Malathion and Sevin that give good control. If you get to the point that they are beyond control like around August and September when the bags have reached their maturity in size, at least pull off as many mature bags as possible. 50% of the bags have female bag worms in them and pulling off all bags you see certainly will be helpful.