Beneficial Insects: The Good Bugs

It may come as a surprise to you that the beneficial insects in our yards and gardens far outnumber the pest insects. Some insects become a part of the life cycle of the plants by acting as pollinators, while others keep harmful insects in check by parasitizing or feeding on them. When we use chemicals to rid the garden of pests, we are also eradicating beneficial insects, and often create an imbalance that effects the overall health of the garden.

Using Beneficial Insects

A number of beneficial insects are available by mail order. Before placing your order, make sure you identify the target pest, because most predators or parasites only attack a particular species or group of pests. Your public library probably has a good book that will help you identify the culprits.

Once you release the insects, you'll need to give them a good reason to stay in your garden. Gardens Alive sells a combination beneficial insect and lure. Once the insects are released, the lure will help to keep them in your garden. This has worked great in my garden, and is a terrific buy.

Beneficial Mites and Insects
Beneficial Species Pests Controlled Tips
Predatory Mite Geolaelaps Fungus gnats, thrips Release a minimum order to establish population early in the season. Good in greenhouses and on houseplants.
Predatory Mite
Phytoseiulus persimilis
spider mites Release 2 to 5 per plant in greenhouses, on strawberries, or on houseplants. They need a moderate temperature (65-75 F)
Western predatory mites
Metaseiulus occidentalis
European red mite Release 50-100 per tree to establish a population or 1,000 per tree to control outbreaks. Also good on strawberries.
Aphid Midge
Aphidoletes aphidimyza
aphids Release 3-5 pupae per plant. Two releases may provide better results. Good in greenhouses, shade trees, orchards, gardens, rose gardens.
Braconid Wasp
Aphidius matricariae
Green peach and apple aphids Buy the minimum order for a garden. Plant parsley-family flowers to provide a food source.
Lady Beetles
Hippodamia convergens
aphids Release minimum order in greenhouses with screened vents. These insects will hibernate in cool greenhouses.
Chrysoperla carnea,
Chrysoperla rufilabrus
aphids and thrips Best to order eggs rather than adults. Distribute widely through the garden - 1 to 3 eggs per plant.
Mealybug Destroyer
Cryptolaemus montrouzieri
mealybugs Use in greenhouses or cage them on houseplants. use 2 to 5 per plant. Nymphs look like mealybugs.
Minute Pirate Bug
Orius tristicolor
thrips, mites Release 1 to 3 per plant. Plant pollen-rich flowers to entice them to stay in your garden.
Scale Predator Beetles
Chilocorus spp.
Lindorus spp.
soft scales Use in greenhouses or on houseplants, citrus, or ornamental trees. Minimum order is sufficient for most needs.
Spined soldier bug
Podisus maculiventris
Colorado potato beetle, Mexican Bean Beetle Release 5 per square yard. Look like stink bugs.
Greenhouse Whiteflies
Encarsia formosa
Greenhouse Whiteflies Release 5 per plant at the first sign of whiteflies. Perform best in warm, bright environment.

The following suggestions will go a long way toward helping you get the most of your hired killers:
  • Release your insects as soon as possible and follow the directions carefully. Every species is unique and should be treated differently.
  • Get a good look at the beneficials before releasing them so that you'll be able identify them in the garden. Many beneficials are very small and you'll need a magnifying glass to identify them.
  • Release some of the insects directly on or near infested plants, then distribute the remaining insects as evenly as possible throughout the garden.
  • A few plants rich in nectar such as catnip, dill and yarrow planted throughout the garden will serve as a food source for your beneficial insects.
  • It can take two to five weeks to see the effects of your beneficials. Keep in mind that you're providing a long term solution, not a quick fix.

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