If you’ve seen tiny bags of silk, twigs and leaves hanging on trees, especially arborvitae and other evergreens, beware. There are 300 to 1,000 eggs in each pouch.
When Bagworms Hatch
In Illinois, bagworms hatch in mid to late June, and control should begin in July once the caterpillars have fully emerged. Once hatched, the little caterpillars climb high into the tree or “balloon” on silk threads into neighboring trees and start feeding at the top of the plant. As they feed, they build their own bags from bits of the plant, which is why they’re so well camouflaged.
Why They’re So Damaging
In short, bagworms can destroy even established trees. Evergreens are especially at risk: unlike a maple, an arborvitae or spruce that loses its needles often can’t grow them back, and the stripped branches die. A heavy infestation can kill a tree in a season or two.
What To Look For
Our division manager, Jeff McGee, shows what to look for in this video on our Facebook page. Check your evergreens from top to bottom. Early on the bags are tiny and look like brown debris; by late summer they can be 1 to 2 inches long.
Treatment And Prevention
- Seeing bagworms now? Reach out as soon as possible. Treatment works best while the caterpillars are young and feeding.
- Hand-pick in fall and winter. On small trees, cutting off and destroying the bags before eggs hatch removes next year’s generation. Bags dropped on the ground can still hatch, so bag them and throw them away.
- Prevent next year’s damage. We use a combination of systemic and topical treatments. These need to start in April or early May.
Even if you don’t see bagworms, it’s not too early to plan to protect your trees. Learn more about protecting trees from insects or our tree and shrub care, or call us at (309) 664-2666.
Rather have a pro handle it? F&W has provided tree care for Bloomington-Normal, Peoria, and Champaign-Urbana, Illinois properties since 1989. Call (309) 664-2666 or request a free quote.