Planting perennials that attract beneficial insects will help keep harmful insects from destroying vegetables and flowers. Beneficial insects are insects that prey and kill harmful. Beneficial insects include the following: Lady beetles, commonly referred to as lady bugs; (Lady bugs eat aphids and other insects); braconoid wasps (which kills caggagewornms, corn bores, aphids armyworms); dragonfiles (eat mosquitoes) , lacewings; syrphid flies or hover flies (eat aphids and look like sweat bees); and groundbeetles (eat caterpillars).
Perennials that attract beneficial insects:
Ornamental onion, flowering onion: (Allium) Attracts hoverflies and other beneficial insects. An attractive perennial with large round shaped flowers on top of a stalk. Size depends on variety. Plant in the fall, the middle of September to early November, before the ground freezes. Plant bulbs 2-3 times deeper than the width of the bulb. Plant small bulbs 4-6 inches apart and large bulbs 12 inches apart. Alliums will grow in any type of soil as long as there is good drainage. Plant in full sun to all morning sun. Fertilize in the spring. Cut the flowers off after they are done, but leave the leaves, which help feed the bulbs for reblooming the next year.
Hydrangeas attract soldier beetles, which eat aphids and cucumber beetles. A beautiful flowering shrub. Plant in the spring in sun to full shade. Hydrangeas need well drained, acidic soil. Add an acidic fertilizer if necessary. Enrich clay soil by adding organic material. Do not over water or over fertilize the first year, when hydrangeas may look stressed. Keep mulch 2 inches deep to keep moisture in. Check the hydrangea for moisture, especially during hot and/or dry spells. Keep the soil moist to prevent wilting leaves. Prune dead stems as they appear.
Yarrow (Achillea): This perennial attracts these beneficial insects: Lady bugs ( ladybird beetle) hover flies and others. An attractive perennial with colorful flowers, many different varieties available. Plant in a sunny location in well drained soil. Yarrow can tolerate average to poor soil, hot weather and dry conditions. Avoid overly wet soil. Best time to plant is in spring.
Catnip (Nepeta, catmint): Attracts soldier beetle (which eat cucumumber beetles, corn rootworms, beetle larvae, and aphids) and other beneficial insects. The are various species; the most well known is Nepeta cataria, which attracts cats. Some varieties have flowers and leafy stems. Catnip grows well in full sun to light shade and well drained soil. In hot climates it can be grown in partial shade. After the first set of flowers, cut down to the ground to encourage bushier growth.
Goldenrod (Solidago): Attracts soldier beetles and big eyed bugs (which eat aphids, leafhoppers, and hoverflies). This beneficial insect attracting perennial has beautiful tiny yellow flowers that boom in late summer and fall. Plant in spring or fall. Goldenrods grow best in full sun and moist, but well drained soil. The ideal soil for goldenrods is poor to average. Soil that is too rich will cause the plant to droop. Goldenrods should be divided in spring or fall every 2-3 years.
Planting perennials that attract beneficial insects can be quite rewarding. Besides helping to keep harmful insects away, these perennials are beautiful and will return year after year to protect your plants and add beauty to your garden.
Taylor’s Guides to Perennials, Barbara W. Ellis, editor.
Dead Snails Leave No Trails, Loren Nancarrow and Janet Hogan Taylor
The Gardener’s Bug Book, Earth-Safe Insect Control. Barbara Pleasant.
Encyclopedia of Perennials, A Gardener’s Guide. Christopher Woods.