Maintaining and Protecting the Beauty and Charm of the Village
Bagworms Are Out to Get Your Trees!
Submitted by Arlene Burke and Susan Moroney, Beautification Committee
Bagworms are caterpillars that molt into moths in the adult stage. They hatch from their eggs in mid-to-late June, then spin silks to catch the wind and balloon to other plants. Bagworms feed throughout the summer and given enough room, they may nest on the same plant indefinitely; they are especially fond of Arborvitae (evergreen members of the cypress family) and Juniper trees. However, they can feed on many kinds of trees including both evergreen and deciduous trees.
These small caterpillars feed on the outer layer of the leaves or needles of their host, causing browning, usually starting at the top of the tree. Young bagworm caterpillars feed on the upper surface of the leaves and may eat enough to create small holes in the leaf. Older caterpillars can consume entire needles or leaves. Heavy infestations, characterized by foliage that has been eaten away, can be unsightly. Such infestations kill branches and decimate whole plants. A healthy deciduous tree or shrub that has been defoliated by these pests may be able to produce a new flush of leaves and survive. However, a defoliated evergreen cannot push out an additional set of leaves and is more likely to decline or die. It is important to note that bagworms pose no threat to human health.
Bagworms are much easier to eradicate when they are small. They are susceptible to chemical treatment into early July. An insecticide with malathion, diazinon or carbaryl can rid you of a bagworm problem, if applied to bushes and trees when the worms are still young larvae.
For more information, please contact the University of Illinois Extension Master Gardener program in Urbana at (217) 333-5900. The Morton Arboretum Plant Clinic at (630) 719-2424 or plantclinic@mortonarb.org is another good resource.
Don’t let bagworms get your trees!