Institute of Food and Agricultural Sciences
Hendry County Horticulture News
Beneficial Insects - Many Are A Gardeners Best Friend
Less than one percent of all insects are pests on plants. Many beneficial insects feed upon harmful ones. Common examples of predators are lady beetles, praying mantises, assassin bugs, ambush bugs, and aphid lions. Spiders also prey on numerous insect pests. Many species of mites do not damage plants but instead feed upon other plant feeding mites. Also, many harmful insects are destroyed by tiny wasp like parasites. It is important to learn to identify these beneficials and to recognize when they are holding pests in check.
A number of beneficial insects and spiders are
extremely efficient in reducing lawn caterpillar populations. A predaceous
earwig, Labidura sp., several spiders, Lycosa spp., ground
beetles, and parasitic wasps are some of the more common predators and
parasites found associated with lawn caterpillars. Quite often these are
misidentified as pests, and are unnecessarily treated with
pesticides. This elimination of beneficial organisms can lead to a caterpillar problem
If such pests as aphids, scales, or whitefly nymphs have a small hole, as if stuck by a straight pin, it is evidence that they have been parasitized by tiny wasps. If predators are present or the pests show signs of parasitism, every effort should be made to preserve the beneficial insects. Delay applying a pesticide and allow the beneficials to control the pest population. Do not apply an insecticide unless unacceptable levels of plant damage are becoming evident.
Give beneficials a chance to reduce pest populations by the following pest management practices:
• In urban areas, do not preventatively spray the lawn, landscape or vegetable garden.
• Scout or examine the lawn, landscape plants and vegetable garden for pests at last once and preferable two times per week during the growing season.
• Apply pesticides only when pest insects are present and causing damage.
• Treat only infected plants in the landscape or vegetable garden and only those areas in the lawn that are infected.
• Research has shown that soaps, oils and B. thuringiensis will effectively control almost any harmful insect or mite infesting landscape plants or vegetable gardens. These pesticides are least harmful to beneficial insects, other non-target organisms and the environment
Lady beetles are among Florida's most beneficial insects. A number of species occur in Florida. Both adults and larvae prey on aphids, scale insects, mealybugs, mites and other soft-bodied insect pests. Adults are oval and most are orange or reddish with black markings, or black with yellow or red markings. The larvae are elongate, somewhat flattened and covered with small spines.
Parasitic wasps are an extremely important and large group of beneficial insects with about 16,000 species occurring in North America. Many of these wasps are very small - most are less than 1/8" long and usually are not noticed. They lay their eggs on or in the body of a host insect and the immature stage consumes the host's tissues over a period of time, eventually killing it. Other more familiar wasps, such as mud daubbers, capture insects, such as caterpillars which they carry to their nests to provide food for the developing wasp larvae. Wasps parasitize many harmful insects such as scales, whiteflies, aphids, leafminers and caterpillars.
All spiders are predaceous, feeding almost exclusively on a wide variety of insects. The majority capture their prey in webs but many of the more beneficial species such as the wolf, jumping and crab spiders do not spin webs. Those that do not construct webs are especially effective in capturing insects that inhabit the soil surface or plant foliage.
Many other beneficial insects including praying mantids, lacewings, big eyed bugs, robber flies and assassin bugs are commonly found in local yards and gardens. By learning to recognize these beneficial insects and what you can do to protect them you can reduce your need for pesticides and learn how to work with nature rather than against her. Good luck and good gardening.
Gene McAvoy is the horticulture agent with the Hendry County Extension Service. Direct your horticulture questions to PO Box 68, LaBelle, FL 33975, e-mail - email@example.com or phone 863-674-4092 or 863-983-1598. You are also welcome to visit the Hendry County Extension Office at 225 Pratt Blvd., LaBelle. Office hours are from 8:00 - 5:00.
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COOPERATIVE EXTENSION WORK IN AGRICULTURE, FAMILY AND CONSUMER SCIENCES, SEA GRANT AND 4-H YOUTH, STATE OF FLORIDA, IFAS, UNIVERSITY OF FLORIDA, U.S. DEPARTMENT OF AGRICULTURE, AND BOARDS OF COUNTY COMMISSIONERS COOPERATING