VIU Milner Gardens and Woodland

How do I attract beneficial insects?

by Vancouver Island Master Gardeners Association

Question: How do I attract beneficial insects to my garden?

Answer: Beneficial insects are any number of species of insects that have important roles in the garden such as pollination and pest control.  They may eat, inject toxin into, or parasitize (lay eggs in) insect pests.  The best known ones are ladybugs and ground beetles but lacewings, assassin bugs, and even earwigs are considered beneficials!  Snakes and birds are beneficial too.

 Ladybeetle larva Syrphid fly larva for cabbage aphids 

Left-hand photo: Ladybeetle larva. Right-hand photo: Syrphid fly larva for cabbage aphids.

Photos courtesy: Linda Gilkeson.

Beneficial insects or “Bennies” need feeding to keep them present in the garden.  If you consider pollination first, then bees need nectar rich plants in the garden while they fertilize your flowers and veggies.  Bee balm and cornflowers, fuschias and herbs do well.

Few gardens are pest free.  If you have noticed a low to moderate incidence of pests in your garden then it’s time to introduce a beneficial predator.  As an example, a ladybug does eat her fair share of aphids but given an adequate food supply (more aphids) the lady bug will lay its eggs and her larvae eat twice what Mum does!  White fly predators, Encarsia Formosa, need to be present even before your pest shows up so you have to do a little homework on what is typical in your area or recall what you had a problem with last year. This is when a garden journal is invaluable! 

Beneficials need what every other living thing needs: food, water, and shelter.  The food varies for each species of predator. Planting flowers to provide nectar will attract bees and humming birds, who eat their fair share of insect pests.  For others, pests such as aphids need to be visible on your leaves and flowers. A bird bath is a good way to provide water. Make sure there are a few rocks of various size in it to allow tiny insects access without falling in. Have a few shallow bowls of water throughout the garden that get refilled when you water. Add a few pieces of fruit to the same bowls now and then as a special treat. 

Here is a list of plants particularly enjoyed by a variety of beneficial insects that will easily fit into any garden and provide a food source for beneficials:  Yarrow, dill, cosmos, fennel, dandelion!, penstemon, alyssum, potentilla, marigold (Tagetes), statice, lobelia, lemon balm, bee balm, parsley, rudbeckia, sedums, veronica, astrantia. 

Most gardens that have a mix of trees, shrubs, perennials, herbs and veggies will very likely have a number of attractant plants.  Keep a journal of what bugs you acquire and plant accordingly next year to attract its doom.  

Season:  During the growing season.

For gardening questions in the growing season, contact the Gardening Advice Line.