Trichogramma

Parasitic WaspTrichogramma are among the smallest insects, having a wingspread of about 1/50th of an inch. Despite its size, this parasitic wasp is an efficient destroyer of the eggs of more than 200 species of moths and butterflies which are leaf eaters in the larval stage. Trichogramma wasps seek out eggs, but do not feed on or harm vegetation. It is a particularly effective biological control agent because it kills its host before a plant can be damaged.

During her 9-11 day life, the female wasp will seek out and destroy about 50 pest eggs by laying an egg inside the pest egg. The trichogramma egg will hatch out into a larvae, and it will consume the pest egg contents. Depending upon climatic conditions a new adult will emerge in about a week.

These parasitic wasps are shipped as pupae in host eggs, glued to one by one inch paper squares, almost ready to hatch out as adult wasps. Distribute in the areas to be controlled. Trichogramma emerge and seek out a variety of eggs which they parasitize and thus destroy.

Some moth eggs attacked by trichogramma wasp are: armyworm, bagworm, European corn borer, peach borer, squash borer, cankerworm, alfalfa caterpillar, cutworm, corn earworm, wax moth, tomato hornworm, cabbage looper, and codling moth. Let the insectary know the type of growing area you are trying to protect, and they’ll send you the appropriate species – pretosium or brassicae for field crops, and minutum or platneri for orchards.

Release should begin when moths are first present and periodically thereafter. Timing is the key to getting a good kill – parasitism – of pest eggs. The use of insect traps to monitor pest presence can be a very helpful tool in determining when to start your beneficial insect releases. Learn about Integrated Pest Management (IPM) here.

General release rates (low to medium infestation):

Release 5,000 trichogramma wasps (1 square) per 5,000 square feet, weekly or every other week, for 3 to 6 consecutive weeks. Moths usually hatch over this time period with the peaks known as “flight.” Depending on the climate you live in, several of these flights can occur during the season.

Interesting Factoid: Adult females use their antennae to measure the size of the host egg in order to determine how many eggs to lay in it.

Related Sites:

The Trichogramma Manual (PDF format) – Texas A&M University

Releasing Parasitic Wasps from Commercial Insectaries – Michigan State University

Good Friends & Foes – Washington State University Extension

Natural Enemies Gallery – University of California Statewide IPM Program