There are gardeners who think that every insect they see is a pest and needs to be destroyed as quickly as possible, when in reality there are some insects that actually help your garden. They catch and eat any number of their harmful cousins. To know which ones are beneficial will help you decide which insects to eliminate and which ones to welcome.

It is important to realize that there will always be some harmful insects in your garden, the key is to keep them under control. Three insects that can help you to do this are praying mantis, ladybugs and lacewings.They are ferocious hunters and most beneficial to have around.

Lacewing larvae can eat up to 60 aphids in an hour. They also eat whiteflies, mites, the eggs of caterpillars and a variety of other small pests.

Ladybugs and their larvae consume up to 40 aphids per hour. They also devour spider mites, beetle grubs, whiteflies and other soft bodied insects.

Praying mantis are fierce predators that will eat a wide variety of pests.

Apart from these three, there are other beneficial insects which are common and can help destroy garden pests.

A variety of predator mites feed on harmful spider mites and thrips without harming plants themselves.

Parasitic nematodes are microscopic worms in the soil that eat their way into numerous soil dwelling pests including grubs, sod webworms, carpenter worms, weevils and destroy them.

Different kinds of wasps are very effective when it comes to insect control. The Trichogramma wasps deposit their larvae into the eggs of caterpillars, from where they eat their way out, destroying the eggs. The Aphytis melinus, another tiny parasitic wasp attacks and kills red scale and Metaphycus helvolus attacks black scale.

Several species of small wasps attack whiteflies in their immature stages. Many other tiny wasps help to control flies when they lay their eggs in the pupae of several types of them, including houseflies.

Most of these beneficial insects can be bought from nurseries and garden supply stores for a few dollars. It is best to release them in the evening because daylight encourages flight. Be aware that without access to prey, water and shelter they will fly away. It is necessary to provide the right environment by growing many kinds of plants in your garden. In return these 'good' insects will help your garden to stay healthy and reduce the need to use chemical pesticides.