Hello, I have had a bagworm problem on a row of shrubs for the past two seasons. Last year, after seeing they were back I started to spray at the end of June. I stopped toward the end of August. As far as I can tell, I see no new bags this year. However, this might be too early. Should I expect them back? Do you advise a spray now as a precaution or is that a waste of time? I have been using Thuricide. Thank you for your valuable information. I have used this service many times.
Wait until you see new small bags on your trees or shrubs before you spray. You will have to monitor for this. Time frame to spray with Bt is usually between mid-June and July. See more on our website http://extension.umd.edu/hgic/bagworms-trees-and-shrubs
Thank you for your very prompt response. Just curious about probability of a return. Is it possible that I could be done with them or is that just a wish? Thanks again mh.
It is possible that you will get more bagworms in the future. They do have a preference for certain types of shrubs and trees. Even if you treat bagworms that you see on your shrubs this year, there is the possibility that more will come in. https://extension.umd.edu/hgic/bagworms-trees-and-shrubs