Beneficial insects rely on insects and plants for food and shelter. Many insects prey on plant pests during one or more life stages; larvae usually have the most voracious appetites. Some beneficial insects are well known, while others are easily mistaken for pests. If your plant is damaged and a beetle is sitting on the leaf, do you automatically assume the beetle did the damage? It's possible that the beetle is sitting there digesting a recent meal of plant pests!
Most people recognize the bright red ladybug as a "good guy," a cute spotted beetle that eats aphids and other plant pests. Learn to also recognize ladybug larvae, the less cute ladybug life stage that eats pests even more voraciously than the adult beetles. With over 450 species of ladybugs in North America, coloring and numbers of spots are highly variable. Adult ladybugs live a few months up to one year, and adult females can lay more than 1,000 eggs during her lifetime. Eggs hatch into larvae, black and red alligator-shaped crawlers a quarter- to a half-inch long. After about 30 days, larvae pupate, usually attached to the underside of a leaf. About two weeks later, the adult emerges and another life cycle begins. In northern Utah, ladybugs have two to three generations.
Lacewings may be the next most-recognized beneficial insect. Both adults and larvae consume large numbers of aphids during their relatively short lives. Lacewing larvae are also called "aphid lions." They look like flattened ladybug larvae with pincer jaws. Lacewings may have one to several generations per year, depending on the climate of the area and that year's weather.
Soldier beetles are common garden allies working behind the scenes. Closely related to lightning bugs, soldier beetles' color and markings vary among the many species. None are especially attractive and are probably often mistaken for pests. Soldier beetles feed on aphids, caterpillars, grasshopper eggs and other soft-bodied insects. There may be one or two generations per year.
Wasps are garden allies that are more often considered pests. Wasps eat many insect plant pests but they also consume spiders, another important group of garden allies. Wasps sometimes damage plants as they chew plant leaves and use the cellulose to make paper nests. And although wasps are docile while foraging, they defend their nests with stinging offense. Most urban and suburban homeowners in limited landscape spaces cannot tolerate wasps. But in places where wasps can nest undisturbed, their landscape contribution is appreciable.
Many other beneficial insects are working as your garden allies. Learn to recognize and protect them.
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* MAGGIE WOLF is a horticulture agent for Utah State University Extension in Salt Lake County. E-mail her at maggie.wolf@usu.edu.
