Many beneficial insects reduce the number of garden pests such as aphids, spider mites, whiteflies, and tomato hornworms. Here are a few of the most common beneficial bugs, usually found throughout North America, that attack insect pests.

Assassin bug
The assassin bug uses its sharp, beaklike mouthpart to stab and kill insects such as caterpillars and harmful beetles. If threatened, the assassin bug can deliver a painful bite to humans.

An adult dragonfly has two sets of translucent, net-veined wings, and its long abdomen is variously colored. It eats a range of pest insects, including flies and mosquitoes. The young, which are aquatic, also attack immature mosquitoes.

Most people don't realize it, but the firefly is a beneficial insect, too. The larvae, which don't fly, consume snails, slugs, and the larvae of various beetles and caterpillars. Fireflies tend to be limited to the eastern half of North America. Unlike most other beneficial insects, fireflies aren't usually offered for sale.

Among the best known of beneficial insects, both green and brown lacewings have large, lacy wings and feeds on a large number of pest species, including aphids.

The adult ladybug, or ladybird beetle, is easily recognizable with its orange body and black spots. Both adult and young ladybugs attack aphids, scale insects, spider mites, and similar pests.

Minute pirate bug
The tiny minute pirate bug is black and white. Both adult and young minute pirate bugs feed on a variety of insects, including aphids, spider mites, and some caterpillars. Like assassin bugs, minute pirate bugs can inflict a painful bite if threatened.

Praying mantis
The praying mantis is the largest (to 4 inches long) predaceous insect gardeners are likely to find, and also one of the most recognizable. It will attack and consume almost all other insects it comes across, including grasshoppers, other beneficial insects-and each other. It's not as common as other beneficial insects.

Spined soldier bug
The spined soldier bug looks like its relative, the stinkbug, but instead of attacking plants, it attacks other insects. This brown, shield-shaped bug eats a wide variety of pest species, including the young of beetles such as the Colorado potato beetle.

Attracting beautiful insects
To attract beneficial insects, limit the use of any pesticides, both commercial and homemade. Because many beneficial insects eat pollen, planting a range of plants with pollen-rich flowers helps, too. Examples of pollen-rich plants include sunflower, dill, sweet alyssum, daisy, yarrow, and goldenrod.

To attract beneficial insects, you'll also need pest insects; when beneficials completely eradicate their food source, they'll leave your garden.

Beneficial insects are available for purchase from a number of sources, including Planet Natural, Bozeman, MT, 800-289-6656,, and Heath's Organic Pest Control, Sugar Hill, NH, 603-823-8500,