How to Use Trichogramma for Natural Caterpillar & Moth Control

Aug 12, 2026

Written by Elaine Sawyer

How to Use Trichogramma for Natural Caterpillar & Moth Control

Trichogramma are minuscule wasps that feed on the eggs of many insect pests.

Various Trichogramma species are used worldwide to control caterpillar pests on vegetable and horticultural crops, as well as in forests and indoor spaces.

This beneficial insect does not kill adult moths, but only targets the eggs. Trichogramma can only work if pest eggs are present. If caterpillars are hatched and there are no eggs to parasitize, Trichogramma are not effective. Timing is everything! Using light or pheromone traps and plant inspections will assist with decisions about when to release Trichogramma to ensure timing is accurate.

Once you know that pest eggs are in the crops, careful handling of this delicate parasitoid is essential. Optimum conditions for Trichogramma release are temperatures between 68-81°F with >60% RH.

Best practices are to release this biocontrol agent as soon as it is received. If necessary, they can be held in the fridge for 2-5 days, but cold storage lowers their survival rate and weakens their ability to locate pests.

In orchards, release at the base of infested trees and release a few upwind to encourage their natural spread throughout the orchard.

1-2 per sq. ft, weekly during moth flight
50,000 to 100,000 per acre, weekly during moth flight

Trichogramma are shipped as parasitized moth eggs fixed to cardboard sheets. Each sheet holds about 125k. The sheets are perforated into 30 small squares, each with 4,000 to 5,000 Trichogramma. Carefully tear the sheets along the perforations and distribute immediately or hold in containers with food until the adults begin to emerge.

To help Trichogramma off to a good start, consider creating an area for them to mate and feed before releasing.

Enclose each square of cardboard in a small, screened paper cup or jar, along with a small piece of cotton moistened with dilute honey or fruit juice. (If honey is too thick, they could get stuck.)
Hold for 2-10 days at 76-78°F.
When the Trichogramma begin to emerge, uncover and place the cups throughout the crop.

Trichogramma are weak flyers and must be well distributed throughout the crop for successful control. Use a Bacillus thuringiensis (Bt) product like Dipel or Xentari to control caterpillars until Trichogramma are well established.

Trichogramma larvae feed on the eggs of many pest moths. Female adult wasps have the uncanny ability to locate moth eggs on the plants. They then insert their own egg in the pest egg and 10 days later a fully formed adult Trichogramma emerges to begin the cycle all over again. Trichogramma are used for many lepidopteran pests, including:

Moths - codling moth, oriental fruit moth, diamondback moth, gypsy moth, tent caterpillar moths and clothing and pantry moths.
Worms and Loopers - cabbage looper, corn ear worm, cotton bollworm, armyworms, cutworms and webworms.
Hornworms and fruit worms (- Tomato hornworm, tobacco hornworm, and fruit worms.
Borers - European corn borer, southwestern corn borer and cane borers.

It's unlikely that Trichogramma will be spotted in the field, but insects like these are the first line of defense against many pests in our environment. Pesticides and their residues can stop Trichogramma as well as the pests they target. Without these beneficial insects in the environment, a vicious cycle begins of pests and chemicals. Preserving our native enemies will keep the pests in check and preserve the natural balance in the ecosystem.