Those little cone-shaped bags hanging off your arborvitae, spruce, or juniper aren't seed pods. Each one is a caterpillar in a case built out of your shrub. On evergreens this matters more than most pests, because arborvitae don't regrow needles on bare branches — what they strip stays stripped. The spray window in Central PA is narrow: roughly mid-June to mid-July.
Free Estimate — Call or Text 717-379-3248People miss bagworms for years because the bag is camouflaged with the plant's own foliage — that's the whole point of it. Two quick checks:
Text a photo to 717-379-3248 if you're unsure. Identification is free, and on this pest the calendar matters enough that it's worth knowing quickly.
This is the part that catches people out. A bagworm infestation on a maple or a sycamore looks alarming and is usually survivable — deciduous trees leaf out again next spring and carry on.
Arborvitae, juniper, spruce, and cedar don't do that. They don't set new buds on bare interior wood. A branch that gets stripped is finished, permanently, and a heavy infestation across a whole plant can kill it outright. On a privacy screen of arborvitae — which is most of what we see this on around Harrisburg — that means a permanent gap in the hedge you planted for privacy.
In the window (June–July): a targeted application while larvae are small and exposed. Coverage is what makes or breaks it — bagworms sit throughout the interior of a dense arborvitae, not just on the outside, so the material has to be driven into the plant rather than misted over the surface. On a mature screen that's a real spray job, not a hose-end pass. Where the timing is early and the population is caught young, Bacillus thuringiensis is often enough and is about as selective as treatment gets — worth mentioning because we keep our own bees and prefer the narrow option when it does the job.
Outside the window: we'll tell you it's outside the window. What we'll recommend instead is hand removal over the winter and getting you scheduled for next June. We'd rather do that than take money for an application that won't work.
Estimates are free and depend on the number and size of plants — a row of twelve mature arborvitae is a different job from two foundation shrubs. Send a photo of the worst plant and we can usually scope it without a visit.
Genuinely effective, and we'd be doing you a disservice not to say so. Every bag still hanging on the plant from autumn through early spring is a female's egg case holding hundreds to around a thousand eggs. Each one you remove before hatch is an entire cluster of next year's caterpillars gone.
On a couple of small shrubs this alone can solve the problem. On a mature twenty-foot screen it isn't realistic, which is where treatment earns its place.
Arborvitae most of all — it's the classic host in Central PA and it's planted everywhere as screening. Also eastern red cedar and other junipers, spruce, and false cypress. They'll feed on a long list of deciduous trees too, including maple, sycamore, linden, and honeylocust, though the consequences there are much less severe.
All of the City of Harrisburg (17101–17104, 17109, 17110) plus Penbrook, Paxtang, Steelton, Highspire, Colonial Park, Lower Paxton, Susquehanna Township, and Linglestown. Also Hershey, Hummelstown, Mechanicsburg, Camp Hill, Palmyra, Middletown, Carlisle, and Lebanon.
Free identification, usually within the hour. If it's June we'll get you scheduled inside the treatment window. If it's September we'll tell you to save your money, pick them off over the winter, and book for next summer. Licensed PA pesticide applicator since 2005, beekeepers ourselves, fully insured.
Call or Text 717-379-3248