...Beneficial Insects in the Home Garden...
Arthropod is any invertebrate animal of the phylum Arthropoda with a segmented body, jointed limbs and an external skeleton, e. g., an insect, spider, or crustacean. To the gardening public, these are BUGS and may be a bane or boon...most insects, spiders and other arthropods found in the yard and garden do not feed on or harm plants. Many are innocuous or just passing through with others feeding on and destroying pest species. In many cases, the activities of these beneficial species can completely prevent or greatly limit pest problems. It is important to recognize these beneficial arthropods so they may be appreciated and conserved!
Beneficial arthropods are categorized broadly as either predators or parasites.
Insect predators actively search out and eat prey insects. Common predators are ladybugs and spiders. Common parasites are tachninid flies and the braconid and ichneumonid wasps. Ladybugs are the most familiar insect predator. Both the adult and larvae ladybug feed on large numbers of small soft-bodied insects such as aphids. All spiders feed on insects or other small arthropods. As well as the familiar web-making spiders, there are many others such as the wolf, crab or jumping spider that do not build webs, but instead move about hunting their prey on soil or plants. Spiders assist in controlling beetles, caterpillars, leafhoppers and aphids.
Woe to the big green tomato worm or hornworm caterpillar. The tachnid fly, an insect parasite, lays eggs on various caterpillars, beetles and bugs, usually near the head. The eggs hatch almost immediately, and the young maggots feed on the host eventually killing it. This fly is rarely observed by the average gardener, and the beneficial activities are often overlooked.
The braconid and ichneumonid wasp is a very large and diverse group of insect parasites. Some are small and attack small insects such as aphids with others living in eggs of various pest insects. Larger parasite wasps attack caterpillars or wood boring beetles.
In the yard and garden, it is important to recognize naturally occurring insect predators and parasites. Before making insecticide applications, check plants for existing beneficial organisms. Their abundance may be enough to provide control. When possible, use insecticides that are selective in their activity or less harmful to the insect predators and parasites.
The predators and parasites mentioned commonly occur in the central Missouri area.
Source: W. S. Cranshaw, Colorado State University Cooperative Extension entomologist. Publication Number 5.550
Posted 7/3/2013
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