Print This Page

Trichogramma Wasps - Newsletter

Dirt Doctor Weekly Newsletter - Trichogramma Wasps


Trees have been having some caterpillar problems.  The preventative treatment for this pest is the release of the beneficial insect called trichogramma wasp.  If the worms are already feeding, killing sprays need to be used.

Various worms, the larvae of moths and butterflies, eat the buds, leaves and flowers of many different species of food crops and ornamental plants.  They can be sprayed and killed with Bt (Bacillus thuringiensis) products, spinosad products or orange oil-based products.  For better effect from the killing sprays, add one ounce of molasses per gallon of spray.  Although  Bt is an acceptable biological product, it will kill butterflies as well as the larvae of moths and should only be used as a last resort and on plants where caterpillar feeding is in progress.  When used, it should be sprayed at dusk.


The better approach is to release trichogramma wasps as a preventative. They can be purchased at organic garden centers, feed stores and ordered by mail.  The 1” cards contain about 3000 moth eggs.  Larger strips have more wasps.  Simply pin the cards or strips on tree trunks or on fences.  The almost microscopic wasps emerge from the sandpaper looking moth eggs and fly off to parasitize and destroy other pest eggs.  Nothing works better for the control of canker worms, greenworms, loopers, armyworms, pecan casebearers, tent caterpillars, webworms and other vegetarian worms. Trichogramma wasps must be put out before the pests hatch and start eating.      


If the wasps are dead or have been eaten by fire ants, they won’t work.  Buy from reputable dealers and control the fire ants with organic techniques.  Vaseline put on the nail or pin used to mount the cards or strips will prevent any existing fire ants from getting to the eggs.  They will eat them like jelly beans if present and have access.

Mail Order Sources: 

Arbico - Arizona Biological Control 

P.O. Box 4247CRB  Tucson, AZ  85738-1247
 (800) 827-2847

BioLogic Company 
P.O. Box 177  Willow Hill, PA  17271
 (717) 349-2789

Harmony Farm Supply & Nursery
3244 Hwy. 116  Sebastopol, CA  (707) 823-9125

M&R Durango 
P.O. Box 886  Bayfield, CO  81122
 (800) 526-4075

Rt. 1, Box 39  Quemado, TX  78877 (800) 832-1113

Peaceful Valley Farm Supply
P.O. Box 2209  Grass Valley, CA  95945
 (916) 272-4769

Rincon-Vitova Insectaries 
P.O. Box 1555  Ventura, CA  93001 (805) 643-5407

To find more information on organics, please visit my website at  If you have any questions regarding this newsletter or any other topic, please join me for my radio show heard in Dallas/Fort Worth on Saturday at 11am-Noon and across the country on Sunday from 8-11am (CST).  Radio

Naturally yours,


Howard Garrett
The Dirt Doctor

Question:  I hung the trichogramma wasps on my pecan tree and within hours ants were eating the eggs. How do I keep the ants away?

Answer:  Apply Vaseline to the pin or nail. The ants won't be able to crawl across to the eggs. One of the most important parts of a successful trichogramma release is to control the fire ants. Most organic gardeners don't usually have a problem with them, but outbreaks can be handled with orange oil drenches, beneficial nematodes, spinosad and/or dry molasses


  Search Library Topics      Search Newspaper Columns