Insects Keep Pests at Bay; Green Thumb with Maree Curran

Article excerpt

EVERYONE loves a bit of help in the garden, and some of the best helpers are happy to work all day, every day, for nothing.

They're called insects and beneficial insects will devote their entire lives to managing pests and diseases in your garden, if you let them.

Much of the pollinating work in the food garden is performed by insects, most notably bees, hoverflies, and butterflies. So it's important to provide nectar sources by planting flowers.

They fall into three broad groups a pollinators, predators and parasites. Pollinators fertilise flowers, which increases the productivity of fruit and vegetable crops. Predators consume pest insects as food. Parasites use pests as nurseries for their young.

Predators, such as lacewings, ladybugs and hoverflies feed on insect pests. Some of the adults feed on pollen, nectar and honeydew, and some on insects. All lay eggs that produce predatory larvae, which feed on aphids, thrips, mites, scale, mealy bugs and caterpillars. Lacewing larvae, known as aphid lions and wolves, feed for 15-20 days, eating 100 plus insects a day.

Most ladybugs are predators with ravenous appetites for aphids and other soft-bodied insects. Adult ladybugs will eat several hundred aphids before mating and laying eggs on aphid-infested plants. The larvae feed on aphids as well. Some ladybug species prefer other pests, like mites, white flies, or scale insects. A few even feed on fungus or mildew a you might see them feeding on cucumber or zucchini leaves if you have powdery mildew. One small sub-family of ladybugs includes leaf-eating beetles. Some beetles in this group are pests, but by far the majority of ladybugs are beneficial predators of pest insects.

Adult hover flies feed on pollen and nectar and are often mistaken for bees. The female lays its white oval eggs amongst colonies of aphid or mites. The eggs yield maggots which feed on aphids and other soft-bodied insects.

Parasites deposit eggs on or into the pest or its eggs. The larva then hatches and ultimately consumes and kills the pest. Parasites tend to be host-specific, that is, they will only attack a particular species of pest. Most parasites are either wasps or flies.

Parasitic wasps and flies are small, and don't sting. …