Eastern Tent Caterpillar

Malacosoma americanum

Up until the 1970′s and 1980′s the Eastern tent caterpillar, Malacosoma americanum, had been considered one of the most common and destructive defoliating insects in the Eastern United States. In late spring and early summer, the Eastern tent caterpillars create unsightly nests or tents in the crotch of branches. The feeding of the larvae in late spring and early summer strips the foliage from trees. Complete defoliation can occur when caterpillar populations are high.

Download Eastern Tent Caterpillar Fact Sheet

Treatment Strategy

If your tree is small, physically removing the tents is a great way to reduce the population of caterpillars on your tree. You can cut the branches the tents are attached to, or remove the tents. Doing this in the evening or at night will maximize the impact as these caterpillars move into the tent for protection at night. We do not recommend the use of ladders for this project. If the tree is too tall or if the tents are too high in the tree, use another method.

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Eastern Tent Caterpillar Treatment Option 1

New soil-applied insecticide technology has made Eastern tent caterpillar easy to control. Lepitect soil application provides a greater window of control than sprayed insecticides, and should be applied as leaves are expanding in the spring. A second treatment may be used thirty days later if larvae are still active.

Application TypeSoil Injection

DIY Product/Equipment Needed:

• Lepitect

Soil Injection Kit

• Gloves

Eastern Tent Caterpillar Treatment Option 2

Spray treatments with insecticides such as Up-Star® Gold can provide excellent control. However, if treating a large tree, foliar-applied treatments may be too environmentally risky. Drift and contact with non-target insects are common concerns, making soil-applied treatments the preferred method for many professional arborists. When choosing insecticides, be sure to choose one that controls lepidopteron insects. Most insecticides do not control this insect type.

Application TypeFoliar Spray

DIY Product/Equipment Needed:

• Up-Star® Gold

• Hand pump sprayer with wand

• Gloves

• Safety glasses

Eastern Tent Caterpillar Treatment Option 3

Another less aggressive sprayed approach is Conserve® SC.   The active ingredient in Conserve® SC, spinosid, is a naturally occurring bacterium found in soil. Conserve® SC can be applied as a foliar spray and is considered non-toxic to people, yet is effective on moth and butterfly insects.

Application Method - Foliar Spray

DIY Equipment/Product Needed:

• Conserve® SC

• Hand pump sprayer with wand

• Gloves

• Safety glasses

Eastern Tent Caterpillar DIY Kit

Option 1

Application Type - Soil Injection

DIY Product/Equipment Needed:

• Lepitect

Soil Injection Kit

• Gloves

Option 2

Application Type - Foliar Spray

DIY Product/Equipment Needed:

• Up-Star® Gold

• Hand pump sprayer with wand

• Gloves

• Safety glasses

Option 3

Application Method - Foliar Spray

DIY Equipment/Product Needed:

• Conserve® SC

• Hand pump sprayer with wand

• Gloves

• Safety glasses

How Is It Spread?

Eggs hatch in the spring at about the same time as leaf emergence on cherry. Young larvae begin building their silken tents in a major branch fork or crotch. The larvae feed for a period of six to eight weeks before migrating to a protected site to pupate. The pupal stage lasts for about three weeks. Adult moths emerge in early summer. Females deposit their egg masses around small twigs where they over winter.

Susceptible Trees

Common hosts for Eastern tent caterpillar include Prunus species such as cherry, plum, and peach, as well as flowering crabapple, hawthorn, and pear. Other hosts include maple, ash, birch, oak, willow, and poplar.

Symptoms

• Stripping of the foliage in late spring and early summer.

• A silky nest is visible in the crotches of branches.

• Large numbers of dark colored larvae are visible both on the tree and in the nest.

Lookalikes

Gypsy moth, Sawflies, Forest tent caterpillar

Related/Similar Problems

None

Timing

Spring and summer

Urgency

Can be high depending on population

Risk of Spreading

High

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