Adult lacewings feed on pollen. Keep them in the landscape so their young will eat insect pests. Photo by Edward L. Manigault, Bugwood.orgMaintaining beneficial insects in the landscape means providing food when insect pests are absent. Adult lacewings, flower (syrphid) flies and parasitic wasps, for example, feed on flower nectar and pollen. Their young devour some of the insect pests that can make a gardener’s life miserable.
Research shows that ample flowers not only sustain adult beneficial insects, but also allow longer survival and production of more progeny, thus increasing the biological control of undesirable insects.
The larvae of lacewings, called aphid lions, use hooked jaws to pierce and kill aphids. Flower fly (syrphid fly) larvae look like maggots as they crawl over foliage, feeding on dozens of soft-bodied insects.
Parasitic wasps lay their eggs on insect prey. The eggs hatch into larvae that devour the prey.
Predatory pirate bugs are a little different in that the larval stage is a miniature version of the adult insect and both eat the same food: spider mites, thrips and insect eggs. Only one-eighth of an inch long when mature, predatory pirate bugs are among the most important controls of these undesirable insects.
To sustain adult beneficial insects, plant early blooming flowers such as basket of gold (Aurinia saxatilis) followed by midseason bloomers such as English lavender (Lavandula augustifolia) and late-blooming goldenrod (Solidago virgaurea).
Plants that attract beneficial insects
Christy Shivell, owner of Shy Valley Native Habitat Nursery & Herbary in Fall Branch, Tenn., reveals some of her favorite plants for attracting and keeping beneficials in the landscape.
• Oregano • Cosmos • Basil • Yarrow • Lovage • Mint • Lavender • Marigolds • Nasturtiums • Golden Marguerites
For more: www.shyvalley.com.
Fred Birdsall is a Colorado Master Gardener and Carl Wilson (email@example.com) is a horticulturist at the Colorado State University Cooperative Extension.
The best perennials for beneficial insects
Ferenc Kiss, nursery manager, and Taylor Pilker, order pulling manager, at Cavano’s Perennials in Kingsville, Md., created their list of the best perennials to attract and keep beneficials in the landscape. Their suggestions stem from personal observations and university research.
For more: www.cavanos.com.
• Salvia • Ajuga • Coreopsis • Rudbeckia • Monarda • Echinacea
• Agastache • Leucanthemum • Penstemon • Pycnanthemum
Mixing annuals and perennials help keep beneficials in the landscape.Be preventive, not reactive to pests
Generally, if you keep the landscape diverse, especially with flowering plants, pest problems won’t be as problematic and will attract natural enemies, said Carol Glenister, president of IPM Labs in Locke, N.Y. IPM Labs supplies beneficial insects.
If a large pest outbreak occurs in the landscape, it simply means the natural enemies aren’t present. But beneficial releases are best when used in a preventive manner, not as a reaction to an outbreak, she said.
Be observant and keep good records to know when a certain pest will break out. “Action four to eight weeks in advance is best,” she said.
Proper identification of pests is important. Release predatory mites for spruce spider mite control, especially on arborvitae. Predatory beetles are available for euonymus scale control. Lacewings and ladybugs are often effective against aphids. Beneficial nematodes help combat grubs and trichogramma parasitic wasps are good against caterpillars.
If you buy beneficials from an insectary, pay attention to the release requirements. Lacewings and some predatory mites need to be released in 24 hours, while nematodes can go in the fridge for a week.
For more: IPM Labs, www.ipmlabs.com.