:: green Lacewings against Aphids

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A common green lacewing (scientifically known as Chrysoperla rufilabris) is widely used in various situations to control many different pests. Many species of adult lacewings do not kill pest insects, they actually subsist on foods such as nectar, pollen and honeydew. It is their predacious offspring that get the job done. The adult lacewing lays her eggs on foliage. Each egg is attached to the top of a hair-like filament. After a few days the eggs hatch and a tiny predatory larva emerges ready to eat the pests. Lacewing larvae are also known as aphid lions. They are tiny upon emerging from the egg, but grow to 3/8 of an inch long. Lacewing larvae voraciously attack their prey by seizing them with large, sucking jaws and inject a paralyzing venom. The hollow jaws then draw out the body fluids of the pest. Of all available commercial predators, this lacewing is the most voracious and has the greatest versatility for pests of field crops, orchards, and greenhouses. Each lacewing larva will devour 200 or more pests or pest eggs a week during their two to three week developmental period. After this stage, the larvae pupate by spinning a cocoon with silken thread. Approximately five days later adult lacewings emerge to mate and repeat the life cycle. Depending on climatic conditions, the adult will live about four to six weeks. Each adult female may deposit more than 200 eggs. For best results, habitats should be provided that encourage the adults to remain and reproduce in the release area. Nectar, pollen, and honeydew stimulate their reproductive process. If these food sources are not available, adults may disperse. An artificial diet called Wheast is available to provide the adults with the necessary nutrition they need for reproduction. Wheast powder mixed with sugar and water is used at Beneficial Insectary to help mass-rear the lacewing. Studies by universities and the USDA have shown that spraying field crops with a Wheast/sugar/water mixture increases egg laying considerably. Lacewing adults can survive the winter in protected places but have a difficult time surviving cold winters.

Lacewing larvae feed on many different pest insects. In general, they attack the eggs and the immature stages of most soft-bodied pests such as: aphids, thrips, spider mites, sweet potato & greenhouse whitefly, mealybugs, leafhoppers, and the eggs and caterpillars of most pest moths. When targeting caterpillars, lacewing used in conjunction with Trichogramma wasps can be very effective. Since Trichogramma attack only the egg stage, the lacewing offers a second line of defense; it feeds on eggs and young caterpillars. Information about the use of Trichogramma is available from Beneficial Insectary, as are recommendations of pertinent scientific literature.

Start early in the season as soon as pest insects are detected. Monitoring is essential. Traps and lures can be very helpful tools for establishing "start dates" and for predicting pest population levels. Initiating natural enemy releases when pest populations are high does not lend itself to successful augmentative biological control. The pest must be detected and releases begun when infestations are at a manageable level. Because every situation is different, numbers of lacewings required can vary significantly from site to site. It is therefore important to monitor the beneficial insect and pest populations. Generally, it is best to start with early release of a relatively low number of lacewings per acre or target planting. It is essential to refrain from using broad spectrum chemicals in order to conserve naturally occurring predators and parasites. Lacewings should be released every 10 - 15 days until their populations are easily detectable or pests are no longer a threat.

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