Several types of caterpillars create tentlike webs in tree and shrub branches in spring. Known collectively as tent caterpillars, they weave unsightly webs and devour plant leaves. The protective webs grow along with the hungry larvae. Depending on the species, these pests may favor small fruit trees such as cherries and crabapples, but they attack many other trees and ornamental shrubs. Defoliated plants are left weakened and susceptible to other insect pests and diseases.
Identification: Eastern tent caterpillars, often mistaken for gypsy moth larvae, grow up to 2 inches long. Fine, reddish hairs cover their black bodies. A white stripe runs down their backs, and pale blue spots line their sides. Other species look similar from afar, but vary in their markings. Adult tent caterpillars are reddish-brown moths with two white bars on their forewings. Their eggs overwinter in shiny, black egg masses that encircle twigs.
Signs/Damage: Large, silky white webs in the forks of tree and shrub branches in early spring indicate tent caterpillars are present. The pests come outside the tents to feed. Branches within several feet of their tents are stripped of leaves.
Control: Effective tent caterpillar control targets these pests in early spring when caterpillars and webs are small. For large trees more than 10 feet tall, consider contacting a professional. For smaller trees and shrubs, GardenTech® brand offers highly effective products that kill tent caterpillars by contact and keep protecting for up to three months:
- Sevin® Insect Killer Concentrate is ideal for treating shrubs and small trees thoroughly to protect against emerging caterpillars and treat active infestations. Used with a pump-style sprayer, the product provides broad coverage and direct treatment of webs and their surrounding areas. Cover all plant surfaces thoroughly, paying special attention to forks where branches meet.
- Sevin® Insect Killer Ready to Spray simplifies treating tent caterpillars before and after their tents appear. The product attaches to a common garden hose to measure and mix automatically as you spray. Cover all plants surfaces thoroughly, and treat tents directly. Caterpillars contact the spray as they go in and out to feed.
Tip: Prune overwintering egg masses from trees and shrubs before they can hatch. Remove webs on cool or rainy days, when caterpillars usually hide inside.
Always read product labels and follow the instructions carefully, including pre-harvest intervals for fruits and other edible crops.
GardenTech is a registered trademark of Gulfstream Home and Garden, Inc.
Sevin is a registered trademark of Tessenderlo Kerley, Inc.
- "Eastern Tent Caterpillar (Malacosoma americanum)" by Ryan Hodnett licensed under CC BY-SA 2.0
- "Eastern Tent Caterpillar Moth (Malacosoma americana)" by Aaron Carlson licensed under CC BY-SA 2.0
- "Eastern tent caterpillar (Malacosoma americanum)" by Whitney Cranshaw at Colorado State University (Bugwood.org) licensed under CC BY-SA 3.0