Diagnosis & Plant Health
Is It Too Late to Treat Bagworms in Richmond, KY?
By September, spraying does almost nothing — the fix is picking the bags off by hand.
Bagworms in Richmond, KY show up every year on arborvitae, juniper, and spruce, and by the time most homeowners notice the spindle-shaped bags hanging in the foliage, the window for spraying has already closed. Treatment timing matters more with this pest than almost any other landscape insect Richmond Tree Pros sees.
Is It Too Late to Spray for Bagworms in September?
Yes — by September the caterpillars have stopped feeding and moved into the reproductive stage, so insecticide has almost nothing left to kill.
Bagworm eggs hatch in late spring, and the young caterpillars feed through summer while building the bag that hides them. That early stage — May through July in Central Kentucky — is when a spray actually works, because the caterpillar has to eat treated foliage to die. By fall, the caterpillars inside the bags have pupated, and the moths that emerge are focused on mating and laying next year’s eggs rather than eating. Spraying a fully formed bag in September mostly wastes the material.
What Actually Works Right Now
- Hand-pick every bag you can reach and drop it in soapy water or the trash — not the compost pile, where eggs can survive
- Check the same evergreen again in a week; bagworms are easy to miss on the first pass against dense foliage
- Prioritize the plants that are most valuable or most visible — a heavily infested arborvitae can lose enough foliage in one season to leave a permanent bare patch
- Mark your calendar for late May next year, which is the real treatment window
The University of Kentucky Entomology bagworm fact sheet covers the full life cycle and is the reference we work from for timing recommendations in Madison County.
When to Bring in a Diagnosis Visit
A single arborvitae with a dozen bags is a weekend project. A hedge row or multiple mature evergreens with heavy bagworm pressure is a different conversation, especially if some of the plants are already showing thin, browned-out sections that won’t fill back in on their own. A documented visit — walking the property, counting bags, and setting a treatment calendar for next spring — typically runs $150–$400 in Richmond, priced up front and the same range as any other documented tree or plant health assessment.
Common Questions
Will the bags just fall off on their own?
No. The bags stay attached through winter, each holding hundreds of eggs, and left alone they become next year’s infestation on the same plant.
Can a heavily infested arborvitae recover?
Often, if the damage is defoliation rather than dead wood. Evergreens are slower to push new growth than deciduous trees, so a bad year can take two or three seasons to fill back in.
Is spraying ever worth it in fall?
Rarely. By the time bags are large and visible enough to notice, the caterpillar inside has largely stopped feeding — hand removal is the more reliable fix at that point.
Related: disease & pest diagnosis · arborist assessment · emerald ash borer treatment. Back to Richmond Tree Pros.
Richmond Tree Pros · Serving Richmond & Madison County, KY · Call or text (859) 310-1209
Last updated: September 12, 2026