Beneficial Insects

One of the alternatives to spraying insecticides is the use of beneficial insects.  Not that long ago I wrote an article about one, the ladybug, but there are others.  Beneficials have been especially useful in greenhouses as the structures can keep the insects contained.  In open gardens they aren’t as effective but if you have a specific problem and use them correctly they can be make a difference in your garden.

The Lacewing  (Chrysopa sp.)
There are many lacewing species, some that feed on nectar and honeydew but others are predators.  The species we use the most as a beneficial feed mostly on aphids.  In some species both the adults and larvae will feed on insects other than aphids also.  It’s a good thing when you find them in your yard. Most lacewings are a delicate green in color with two pairs of wings and golden eyes.  The wings are large and transparent. The common green lacewing is found throughout North America. Lacewings are sometimes confused with dragonflies but lacewings fold their wings over their bodies while dragonflies hold them out to their sides.
    Lacewings over-winter as adults usually in leaf litter.  Come spring the adults lay eggs.  Eggs are laid at night.  A female can produce 100 to 200 eggs that are laid at the end of long stalks. They are often laid nearby aphids.  When the eggs hatch in 3 to 6 days, the young insects descend on the aphids and feed. They are fast and have large pinchers with which they suck out the body fluids of the prey.  The larva doesn’t stop with aphids and will feed on any insect small enough for them to handle, including caterpillars, insect eggs, thrips, small worms, immature whiteflies and others. Larvae are slender with a humpbacked shape and have bristles that sprout from the sides.  They collect bits of food and debris to hide themselves from birds. Larvae go through 3 instars, which last two to three weeks.   Adults will feed on pollen, nectar and honeydew along with mites and aphids.  The lifecycle can be influenced by temperature and there may be several generations per year.
    The more predaceous species are bred as biological pest control.  They are generally sold as eggs.  They have a spotty record of success in the home garden and seem to be better used in greenhouse or contained settings and in higher humidity settings.  You can improve their chances of staying around by having nectar and pollen sources available.  To increase the success of any “release”, monitor the insect infestation.  If there isn’t enough for them to eat, they will not survive or as an adult leave the area.  Once the lacewings are released do not use any broad-spectrum pesticide.
    You can attract lacewings by planting things like dill, coreopsis, cosmos, sunflowers and dandelions.  I suspect most of us won’t have to plant dandelions; we just might need to rethink killing them, though.

Trichogramma 
Trichogramma is a wasp that preys on gypsy and codling moths.  The wasps are very small, 4 to 5 would fit on the head of a pin and they do not sting.  The wasps lay their eggs inside the eggs of the moth.  There are over 200 species but only a few species that are used as beneficials.  They target different species of moths.  T. brassicae is the one you need for your home garden.  T. platneri is used for grapes. These wasps are the most studied and released beneficials in the Southwest.
    When you receive your order of wasps they are actually parasitized moth eggs.  The strips with the eggs are hung on branches near where you have seen caterpillars.  12,000 Trichogramma will treat up to 500 square feet.  The wasps themselves will actually travel great distances so if you don’t really have a problem the wasps will move on.
    To use in the garden you need to wait until you see signs of caterpillar damage.  Select the wasp that will target your problem—otherwise you will be wasting your money.  Beneficials can be a good alternative to pesticides but make sure you use them appropriately for the best result.  A search on the internet will provide you with several resources for purchasing beneficials.  Below are a few.

Gardens Alive
(513) 354-1482
5100 Schenley Place, Lawrenceburg, Indiana 47025
www.gardensalive.com

Arbico Organics
www.arbico-organics.com
800-827-2847 or (520)-825-9785
PO Box 8910
Tucson, AZ   85738-0910

Peaceful Valley Garden Supply
P.O. Box 2209
125 Clydesdale Court
Grass Valley, CA 95945
(530) 272-4769 Toll Free (888) 784-1722
 Email helpdesk@groworganic.com
www.groworganic.com