Gardens are full of life. The gardener's crops may be damaged by some organisms called pests, but they are also helped by a wide range of other organisms, called beneficials. Researchers from Cornell University estimate that beneficial insects save farmers at least $4.5 billion in pest control each year. Many of them might be helping you in the garden without your knowledge.

Examples of beneficials:

Everybody recognizes the lady beetle (a.k.a. ladybug or ladybird), but not everybody recognizes their immature form, which looks like a little alligator. Both forms are voracious predators, devouring a wide range of pest insects.

The aphid midge, Aphidoletes aphidimyza, is a tiny fly that resembles a little mosquito. It lays its orange eggs near aphid clusters, and they hatch into bright orange maggots that eat more than 60 species of aphid.

Some parasitic wasps lay their eggs inside caterpillars and other pests. Their offspring develop inside the pests, killing them as they grow.

Ground beetles are a diverse family that includes big black shiny beetles that eat insects, slugs, snails, caterpillars, and grubs.

Hover flies look like little bees because of their black and yellow stripes. You will see them hovering near flowers, looking for nectar to eat, and near aphid clusters, looking for places to lay their eggs, which hatch into aphid-eating maggots.

Beauveria bassiana is a common fungus that kills insects in cool weather. It is the active ingredient in the insecticide Mycotrol, which is approved for organic production.

Several strains of the common bacteria Bacillus thuringiensis form a lethal toxin when they are eaten by certain insects. Commercial formulations of this bacteria include Dipel, which kills caterpillars, and Novodor, which kills some beetle species, including the Colorado potato beetle. Although these bacteria occur naturally, some products (e.g., M-One) have been developed from genetically engineered strains, and are prohibited by organic standards.

Although companies rear beneficial insects for sale, it seldom makes sense to release them in a garden because they usually fly away. Beneficial insects are most common in diverse settings, with plenty of different food sources. Flowering plants often attract them. Pesticides often kill them.