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Volunteer Master Gardeners will be available Tuesdays, from 6-8 p.m., at the Senior Center, located at 6th and Maple in North Branch, in conjunction with our fall class series. They are also at the Lindstrom Farmers' Market on Saturdays, from 8 a.m.-noon in the parking lot of St. Bridget’s Church, located at 13060 Lake Blvd., to answer your gardening questions.

You can also leave your question at 651-674-4417, ext. 18. Depend-ing on the volume of calls, you should get a response within a couple of days. Or try 'Ask a MG' on the web at: www.extension.umn. edu/askmg.

Even though we have seen many new and unusual insects this summer at the Plant Clinic on Monday nights, lace bugs are a problem every summer.

Katharine Widin is a plant pathologist, who owns Plant Health Associates, a horticultural consulting firm in Stillwater. She has researched lace bugs and parts of my article are taken from her findings.

Lace bugs are named for their transparent, lacy wings. They are members of the insect order Hemiptera which includes bed bugs, plant bugs, and harlequin bugs. They feed only on plants and injure them by sucking sap from the under-sides of leaves.

Lace bugs are relatively small insects about 1/5 inches long. They have sculptured wings that are held flat over the back. They feed on the underside of leaves, producing irregular white or yellow spotting that is evident on the upper leaf surface. Droplets of a varnish-like excrement also are deposited around feeding sites. More than 150 lace bug species occur in North America, with the most damaging species found in the eastern U.S.

There are a number of different types of lace bugs that feed on trees and shrubs, and they tend to be specific in terms of their plant hosts. Some of the most common plant hosts affected by lace bugs are white and burr oak, hawthorn, serviceberry, cotoneaster, basswood, walnut, willow, hackberry and azalea. The insect also attacks some herbaceous plants, such as chrysanthemums.

Lace-bug damage on trees and shrubs is usually evident by mid-summer. Feeding causes a blacked or scorched appearance on infested leaves. Upon closer examination with a hand lens, the leaf surface will appear to be dotted with tiny white spots. Leaves look dry and leaf ends may curl. Heavily infested leaves can turn brown and drop prematurely. The undersides of infested leaves are often covered not only with the bugs themselves, but also dark, shiny, varnish-like drops of excrement and old skins that are shed as the insect molts.

Many infestations of lace bugs are not serious and do not need to be controlled. Most damage is cosmetic and plants are rarely harmed by the infestations. They have many natural enemies, such as lace wings, lady beetles, assassin bugs, spiders, and predatory mites. These can help keep populations at manageable levels. In severe cases, infested plants can be weakened by lace-bug feeding, particularly if plants are hit hard in consecutive years or if plants have other stress factors such as drought or construction injury, or have been recently transplanted. Lace bugs are not necessarily a problem every year but should be monitored and controlled early if they become a continuing issue for ornamental plants.

In cases where the host plant has other health problems or there are economic or aesthetic reasons why the infestation should be controlled, insecticide sprays can be used. Try the least toxic alternatives first, such as strong sprays of water, especially directed at the undersides of leaves where bugs thrive. Also try insecticidal soap, horticultural oils, or pyrethrins before using other, more toxic insecticides, which can also harm beneficial insects. Spray host plants when bugs are present and be sure to thoroughly cover the undersides of the leaves. Use only insecticides labeled for both the pest and the host and always follow label directions.

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Free class September 26––Feeding the birds, Carol Henderson, supervisor of the DNR Non-game Wildlife Program. He is also the author of several books, including ‘Landscaping for Wildlife’ and ‘Wild about Birds.’ Join us as he talks about how to attract a variety of wild birds to your feeders throughout the seasons.

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