Q: I have bagworms on my arborvitae. When should I spray?
A: Generally, bagworm larvae hatch from overwintered bags about the middle of May. With the cooler and wetter than normal weather we have been experiencing, you might expect hatch of larvae to be delayed.
Nothing beats actual visual inspections to detect the presence of bagworms. Due to their small initial size after hatching, they may be difficult to see at first, but with patience, they come into view.
Spraying should be applied early in the season, starting now. Any insecticide having bagworms on the label will work when applying early in the season.
There are a wide array of chemicals labeled for use against bagworms. What is more important than the final product-of-choice is how products are used.
• Read and follow all label instructions to ensure proper dosage rates.
• Do not merely treat peripheral foliage, but strive to achieve thorough coverage including inner foliage where bagworms may be hidden.
• Treat al of the infested trees and shrubs; not just those which are most heavily infested, because bagworms will eventually roam and re-infest adjacent hosts.
• Conduct follow-up inspections and apply an additional insecticide treatment if necessary.
For more information contact the OSU Extension Center, 14001 Acme Road in Shawnee at 273-7683.
