Q.I’ve Read A Lot About Treating For Bagworms But Do You Have To EVERY Year?
It’s been suggested to treat bagworms on my honeylocust TWICE a year, is this necessary? My pines are treated once a year. Thank you!
Certified GKH Gardening Expert
If you are having heavy infestations of bagworms you may want to apply the pesticide every week for four weeks beginning in late May, according to a Kansas extension publication. The Ohio publication mentions two applications, because they don't all hatch at once, but the second one is soon after the first application. The Nebraska publication also mentions two applications - one in mid June and again in early July for best control.
So it is up to you. If you are achieving control with one application, stay with it. If you aren't seeing any bags, you can skip a year. A few bags won't defoliate a tree, but it does leave the possibility of more than 1,000 eggs left for next year. Here is lots of info about bagworms. :)
https://bygl.osu.edu/index.php/node/1978
https://bygl.osu.edu/index.php/node/1795
https://nfs.unl.edu/documents/foresthealth/bagworms.pdf
https://bookstore.ksre.ksu.edu/pubs/MF3474.pdf
https://www.gardeningknowhow.com/plant-problems/pests/insects/treatment-bagworms.htm
