Use beneficial organisms to control pests.

Beneficial organisms fall roughly into 2 categories: predators and parasitoids. Predators are usually generalists and feed on a number of different pests. Parasitoids are more specific and many can develop in only one host species. There are many predatory and parasitic insects, but there are also predatory mites and beneficial nematodes (microscopic worm-like organisms).

It is important to have an accurate identification (preferably the Latin name) of the pest you are trying manage, so you can buy a beneficial that actually feeds on it. You can take specimens to the County Cooperative Extension Office, (look under "County Government Offices" in the phone book). Private consultants also provide identification services. See the Yellow Pages under "Horticultural Consultants." Calling ahead to ask when to bring in your specimen and how to preserve it will save time.

Most beneficials are extremely sensitive to pesticides (often much more so than pests!), and you may have to wait for pesticides you have used recently to degrade before introducing beneficials into your garden.

If you are buying beneficials from a nursery or hardware store, ask for the name and phone number of the beneficial producer. Ask the staff in the retail store if the beneficials have been kept in a refrigerator. Don't buy anything that has been stored on a shelf.

Beneficial organisms are living creatures and must be handled with care if they are to remain alive. They will need food when they arrive in your garden, so don't order them unless you have pests for them to eat.

You will have the most success with some beneficial organisms (consult the insectary) if you release them at the first sign of a pest problem. This requires monitoring your garden, getting out and looking at leaves and plants to find pests before their numbers reach high levels.

Often it is the immature stage of a beneficial insect that provides the best pest control, while the adult feeds mainly on nectar and pollen. By adding nectar- and pollen-rich plants to your garden you can encourage the beneficials to stay and reproduce. Try plants with numerous small flowers such as yarrow (Achillea spp.), sweet alyssum (Lobularia maritima), native buckwheat (Eriogonum spp.), California lilac (Ceanothus spp.), and coyote bush (Baccharis spp.). Flowers in the daisy family, such as asters and cosmos, and herb plants such as fennel, coriander, caraway, dill, and chervil (if allowed to flower) are also useful.

Many pest insects, such as aphids, scales, and mealybugs, are tended by ants that will attack and fend off beneficial insects. Use sticky barriers (Tanglefoot^®, Tree Sticky Barrier^®) around the trunks of trees or shrubs to exclude ants. Prune branches away from buildings or other objects that might provide ants an alternative route into the plant.