Are caterpillars chewing on your cabbage?  Aphids browsing your Brussels sprouts?  Cucumber beetles snacking on your squash?  Keeping insect pests from attacking your garden veggies can be a problem, but help is on the way:  Just invite your neighborhood beneficials to the banquet in your garden.

Beneficials are insects that help gardeners by making their living from garden pests in two main ways:  by parasitizing them or by preying on them.  Parasitic beneficials depend on pest insects for survival because they must lay their eggs in or on them.  Their immature stages develop in or on the pest insect, feeding on its body and killing it.  Predators are adult beneficials that eat pest insects.

Lady beetles (lady bugs), assassin bugs, lacewings, soldier beetles, spiders, and predatory wasps are all examples of beneficial insects.

You don't need to order beneficials from a garden catalog; most are already present in your garden.  Your job is to give them the food, water, and shelter they need to thrive, and they will reward you by patrolling your garden.

Here are eight things you can do to attract beneficial insects into your garden and keep them there:

• Avoid the use of pesticides.  Pesticides tend to be indiscriminate, killing beneficial insects as well as insect pests.  If chemical control is necessary, use the least disruptive materials, such as soaps, oils, microbials, or botanicals.
• Create a garden that celebrates diversity.  Include both annual and perennial ground covers, shrubs, trees, turfgrass, and some permanent arrangements, such as stone paths and decorative rock accents, which will provide shelter for insect predators.  Clumps of native grasses make good overwintering sites for a variety of predatory insects.
• Plant lots of different kinds of flowers.  Flowers provide pollen and nectar that beneficials need and that will sustain them when pest populations are low.  Flat-topped flowers, such as dill, parsley, cilantro, and Queen Anne's lace, are especially attractive to tiny parasitic wasps – some of the most effective beneficial insects in the garden.
• Provide water.  A shallow dish of water filled with pebbles or gravel and placed in a sheltered area will give small beneficials a safe place to slurp.  Change the water regularly and avoid a puddle to prevent mosquitos which may harbor West Nile Virus from laying their eggs there and multiplying.
• Plan for a full season of bloom.  Keep beneficials in your garden year-round by including varieties of flowering plants that bloom throughout the year.
• Go native.  Allow some corners of your yard to grow naturally.  Native beneficial insects love native vegetation.
• Tolerate a small number of pests.  This will provide a continuous food supply for beneficials.  Try “sacrificing” some plants in the garden, or if resorting to pesticides, make spot-treatment applications, leaving reservoirs of pests on which beneficials can survive.
• Eliminate ants.  Ants interfere with the ability of predators to control aphids and scales.  Applying a sticky material such as Tanglefoot to the base of affected plants will keep ants away.

For more information on beneficial insects, a great resource is the Natural Enemies Handbook:  The Illustrated Guide to Biological Pest Control.  It can be ordered through UC ANR as either a hardcover book or an electronic download.  An additional resource is UC IPM's Quick Tips on Beneficial Predators (free PDF download).

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system. To learn more about us and our upcoming events, and for help with gardening in our area, visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu (preferred) or call (530) 538-7201.