Let bugs eat bugs.

Written by horticulture  |  12. December 2003

Over the next few months, I will be covering an alternate form of insect control, namely predatory insects and their applications. For over 30 years we have been relying on pesticides that were chemically synthesized. However, before that, one of the predominant form of insect control was predatory insects. These "good bugs" feed on the damaging insects in our landscapes and can help minimize and sometimes prevent costly damage. One note about using predatory insects- they can be fickle helpers. By that I mean that once they have done their job and their food source is depleted, they will move onto greener pastures. So if you think that one release of any of the beneficial insects are going to solve all the problems on the landscape forever- think again. Normally multiple releases are required every year to keep damaging insect populations in check. Another note about using beneficial insects- after their release, NO PESTICIDES should be used on either the landscape plants or the lawn, as they can have a detrimental effect on the predatory insects you are releasing. The first group of "good bugs" I am going to cover are caterpillar controls. The most effective controls are the green lacewing and Trichogramma. Green lacewing nymphs (Chrysoperla rufilabris) are one of the few predators that will feed on just about anything it can find (including each other) including aphids, mealy bugs, spider mites, leafhopper nymphs, caterpillar eggs, scales thrips and whiteflies. To control caterpillar eggs, it is recommended to use a combination of eggs and nymphs to get a longer control window in the early spring before the caterpillar eggs hatch. The nymphs will begin feeding as soon as they are released and should be placed on or near to the caterpillar egg mass. Lacewing eggs should also be placed near the egg masses so that the hatching larvae will be close to their food source. The adult lacewing feed on nectar, pollen and honey and are nomadic. The adults should be used later in the season as they will lay their eggs near any egg masses deposited in the late summer by adult moths. The one downfall to these insects are that the eggs are a favorite food of ants and need to be protected from them. The other control method is the release of Trichogramma minutum, Trichogramma pretiosum, Trichogramma brassicae. These are parasitic mini wasps that are egg parasitoids. The adult wasp lays its eggs in the caterpillar eggs, killing it and providing an environment for the wasp to grow. To use these wasps, careful planning is involved as well as knowledge of the caterpillars lifecycle. A good rule of thumb is make your first release in the spring before the caterpillar eggs hatch and another release in the late summer when moths are seen flying. These mini wasps are effective against more than 150 different species of caterpillars including borers, webworm, loopers, leafworms, fruitworms, cutworms, bollworms and armyworms. I would love to hear from you, if you have any questions or have used these beneficial insects before. Contact me at aplantdoctor@hotmail.com or call my office at 631-691-2381 or on my cell phone at 631-404-6802.

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