How to Destroy Tent Caterpillars

Tent caterpillars eventually become harmless moths, but they can cause a lot of trouble before they do.

Tent caterpillars, also known as tent worms, refer to the immature larval form of numerous moth species. They are generally harmless, not being poisonous or spreading disease, but their large fibrous colonies can be visually unappealing. They can also consume great quantities of leaves during population booms, weakening or even killing trees. Prompt disposal by removing specimens by hand, destroying egg cases and webs, and the use of insecticides and other traps can limit their population and prevent substantial damage.

Things You'll Need

• 1-gallon or larger plastic bucket
• 1-gallon of plain bleach
• Rubber gloves
• Bacillus thuringiensis (Bt) pest spray

Instructions

1. Fill the plastic bucket with bleach to within 2-inches of the bucket's rim and bring it to the tree that contains the colony. Put on the rubber gloves and remove any mature caterpillars from the tree. Drop them in the bucket to kill them quickly.

2. Examine the tree for egg masses, which are about an inch long and wrap around small branches. Remove them by hand and drop them into the bucket.

3. Examine the tree for webs, often called "tents," with caterpillars inside them. Remove the tents by hand and drop into the bucket. Uninhabited tents can be removed and disposed of however you wish.

4. Apply Bt pesticide to the leaves of the tree. This will kill caterpillars that feed on the treated leaves without harming other creatures.

5. Repeat Bt application for any other trees that you suspect are infested by or being eaten by tent caterpillars.

6. Dispose of bleach according to your local regulations.

Tips & Warnings

• Tent caterpillars are more of a visual nuisance than a threat, and they can only kill trees during extreme population explosions which tend to be brief; it is not necessary to exterminate them from your yard every year.

• Removal of tents should be done in the evening or morning, as the caterpillars will be more likely to be inside them.

• Pesticide is largely ineffective against egg masses, and chemical pesticide sprayed on trees can harm beneficial creatures. Bt pesticide is a bacteria-based pesticide that will kill caterpillars without harming other wildlife.

• You can augment hand-removal of tent caterpillars by placing buckets of water against a tree trunk; caterpillars will fall in and drown. The use of sticky adhesive around a tree trunk can also capture caterpillars, but may harm other wildlife as well.

• Do not set fire to the tents, as you risk burning yourself and the tree.

References

• University of Kentucky on Tent Caterpillars
• New York Department of Environmental Conservation on Tent Caterpillars