Japanese beetles and webworms

Asked January 7, 2016, 5:49 PM EST

I recently learned about a product call Bayer Advanced Tree and Shrub Pest Control ....it says it can be applied in the Fall to help next Spring....is it too late to use it now since we have had such a mild winter? I live in Northern Baltimore County....our ground is only frozen about 1/2-1 inch down and we could dig around that...since it is supposed to rain this weekend...or would that be a waste of time since it is getting so cold now....should we just wait until the Spring? Thank you . B. Smith

Baltimore County Maryland

1 Response

What plants are japanese beetles bothersome on?
We always suggest the least toxic alternative first, and only if it's truly a problem.
In the case of webworms, unless your plant is brand new and small, they are not of concern, and we'd suggest either leaving them (the plant can take it, and these are a good food source for song birds.) If you don't like them, you can also just prune out reachable branches and smoosh them and discard.
Japanese beetles can be a pain, but lately their populations have been variable due to weather at the times that they are trying to lay eggs in the summer soil for the following season. We had a mini-drought this year at that time and they might not be too bad. Depending on the size of the plant you are seeing them on, you can get pretty good control by going out in morning or early evening and sweeping them into a bucket of soapy water. They are not good flyers and tend to drop straight down when disturbed.
It is very important to be careful with the product you mention. The active ingredient in it is imidcloprid, which is a product of concern as far as bees and pollinators go. It is a systemic insecticide which is taken up into the plant and is distributed to the flowers. If the plant you are treating is pollinated or visited by bees, it would be better not to use this product.
If you do decide to treat, now is not the time. Late March would be better. Read and follow all label instructions carefully.
Here is our webpage on Japanese beetles: http://www.extension.umd.edu/hgic/japanese-beetles
and webworms: http://www.extension.umd.edu/hgic/fall-webworm-trees