Beneficial insects can make a difference in garden

There is an army of beneficial insects in your garden doing all they can to control bad insects. And they won't harm your plants. So when you see some of these insects, realize they need somewhere to rest and then go on with their business.

The beneficial insects kill pests, often by parasitizing, which is feeding off a host, such as aphids. If given a chance, beneficial insects can prevent or greatly limit pest problems. Learn to recognize these beneficial insects so you can weigh your options before reaching for pesticides.

We are aware of the predatory habits of the adult lady beetles (ladybugs). We recognize their orange, shiny, convex, half-dome shape along with their traditional black spots. But many are not familiar with their larvae stage, when they look like mini alligators. These "alligators" are the real eaters of bad insects.

Usually, the beetle's life cycle lasts about a month. In the spring, overwintering adult females find food such as aphid colonies and lay eggs. In three to five days, the little orange and black larvae appear. During their lifetime, they will eat as many as 5,000 aphids.

Green lacewings also are very beneficial predators and common in gardens where pesticides aren't used. The adults are delicate, pale green insects about three-fourths of an inch long. Their four wings have many veins, which give them the netlike or "lace" appearance. They may be mistaken for moths, except they have a characteristic fluttering flight when disturbed. They have an objectionable odor when handled.

Lacewings have a distinctive characteristic. They lay pale green eggs on tips of threadlike stalks or pedestals on leaves. This protects them from pests such as ants feeding on aphid honeydew below the eggs.

The lacewing eggs hatch into light brown larvae. They have large sickle-shaped mandibles that consume lots of aphids. We call them aphid lions.

Lacewing larvae feed on mealy bugs, small scales, mites, whiteflies and other small insects. And when they haven't got anything else to eat, they eat each other. They do most of their foraging at night.

Other evidence of beneficial insect activity is empty skins of aphids we call mummies. Parasitic wasps create them.

If you find these mummies on plants, don't wash them off.

The parasitic wasps lay eggs inside live aphids and/or caterpillars. When larvae emerge within the bad guys, they essentially eat them from the inside out and they become mummies or dried-up bodies. These wasps will not hurt you.

As a skilled gardener, inspect your plants for signs of beneficial insects. And when you do, do not use insecticides. They are slow to re-establish after insecticide applications, giving a competitive advantage to pests.

MELONS AND MORE MELONS

Nevada Cooperative Extension master gardener Helen Brown will share her formula for successfully growing watermelons, cantaloupes, squash and other vine crops at 9 a.m. Saturday at Acacia Park, 50 Casa Del Fuego in Henderson. For more information, call 257-5555.

IRIS FLOWER SHOW

The Southern Nevada Iris Society is having its annual iris show, "Rainbow in Bloom," from 9 a.m. to 4 p.m. Saturday on the lower level of the Galleria at Sunset mall, 1300 W. Sunset Road in Henderson. Dozens of varieties of irises, including this year's new introductions, will be on display.

Irises are very colorful plants and easy to grow in Las Vegas. Learn more about the "orchids of the desert," as they are called. Identify your favorites and make a wish list to purchase them in July at Star Nursery. For more information, call 361-4985.

CACTus SALE

The Cactus and Succulent Society of Southern Nevada and Moon-Sun Cactus and Koi Gardens, 6430 McGill Ave., are having their annual cactus and art sale from 9 a.m. to 4 p.m. today. For more information, go to www.moon-sunlandscapes.com or call 645-2032.

Linn Mills writes a garden column each Sunday. You can reach him at linn.mills@ springspreserve.org or call him at 822-7754.