Interest in organic gardening has grown rapidly over the last few years. As consumers become more conscious of the health risks associated with chemical pollutants, the gardening trend has turned toward natural products to control harmful garden pests. While organic pesticides are generally safer than traditional chemical bug killers, they still present some risk.
Using beneficial insects in your organic gardening to control crop-damaging pests is the option that is safest and healthiest for people, plants, and pets. The species and number of beneficial insects required for pest control is determined by what type of produce you are growing, how much area needs to be protected, what pest you need to control, and environmental factors such as temperature and humidity.
Trichogramma
These tiny wasps (with wingspans of 1/50 of an inch) are the most widely used natural parasitic insect, capable of destroying the eggs of over 200 species of butterflies and moths on many agricultural crops, fruit and nut trees, and ornamental plants. Female trichogramma lay their eggs inside the host eggs, destroying potential caterpillars that eat the leaves of garden plants. Trichogramma can be purchased as pupae attached to small black squares of paper, which the gardener places in the crooks of trees or in the leaves of plants when the pupae begin hatching.
Ladybugs
These small predator beetles consume aphids, thrips, scale insects and other soft-bodied garden pests and their eggs. Ladybugs can be used as pest-control agents for agricultural crops, orchards, home gardens and greenhouses. They are purchased and released as adults, or you may find colonies of ladybugs overwintering in crevices on the north side of your house or in hedges. Once the garden pest population is reduced, the ladybugs will fly away in search of another food source. Supplemental food sources may attract them to your garden naturally, and tempt them to hang around your garden longer.
Praying Mantis
These bugs are voracious predators that will eat any other bug in their paths, and larger species may even prey on frogs, birds, and rodents (although they can’t bite humans). They are masters of camouflage, often lying in wait to ambush their prey. Praying Mantises are purchased as egg cases, and require several weeks of warm weather before they hatch. Unfortunately, they will eat beneficial insects as well as garden pests, and may even eat each other. On the plus side, they are the only predator insect fast enough to catch mosquitoes, and will eat moths that come out at night.
Whitefly Parasite
These minute wasps lay their eggs inside immature white-flies, killing them as the parasites hatch. They are most effective once the average temperature reaches 62 degrees F, since they will not seek out new hosts at cooler temperatures. They are best reserved for indoor gardening, since they may hatch while packaged and escape into the atmosphere before you have a chance to place them on the plants.
Aphid Midges
These predators lay their eggs near aphid colonies, and as the larvae hatch they begin feeding on aphids by draining their body fluids. Aphid midges are most popular for pest control in greenhouse environments, where they can work most effectively in the high humidity and are sheltered from the wind.
Green Lacewing
The predator larvae of the green lacewing are voracious eaters, and may be used to control aphids, thrips, mealybugs and white-flies in organic gardens. The larvae inject venom into these soft-bodied garden pests, sucking out the body fluids of their victims. Purchase them as eggs or about-to-hatch larvae, and sprinkle them over the garden.
Mealybug Destroyer
The mealybug destroyer is a predatory beetle which feeds on aphids and soft scale. Their larvae look similar to mealybugs, and may make the problem appear worse before it improves. Mealybug destroyers lay their eggs among the eggs of other insects. As the predator eggs hatch, they eat the pest eggs and young mealybugs, reducing the future population by interrupting the mealybug life cycle. Adults will fly off in search of other food if the mealybug population is low, making them more effective for pest control for greenhouses than outdoor organic gardens. Keep vents and windows closed when first introducing them to the indoor garden.
Beneficial Nematodes
Beneficial nematodes are microscopic worms that can destroy over 230 different pests that live in your yard and garden, including fleas. Nematodes occur naturally in most soils, but may not be populous enough for effective organic garden pest control. They will destroy pest insects in and on the soil as well as those that bore into trees and shrubs, while posing no harm to other beneficial insects, earthworms, people, pets, or plants.
Gardeners should be able to find these beneficial garden insects through suppliers of organic gardening products, either brick-and-mortar stores or online, but you can also attract them naturally by growing a diverse variety of plants that provide food and shelter. A source of water also helps attract beneficial insects to your garden. Flowers, fruits and vegetable plants that are native to your region are the best choice for attracting beneficial insects to your garden.