GardenLine | Common Saskatchewan Pests | Lace Bugs

Sharon Faye

Lace bugs are small delicate insects that injure leaves by sucking out plant juices. Leaves may appear moulted or discoloured by black tar- like specks on the underside surface. Lace bugs appear to be out in full force during mid- August.

Appearance: Lace bug adults are only 3-6 mm long with a sculptured lacelike appearance to their wings. The nymphs (immature lace bugs), do not have lacy wings but are usually spiny. There are many species that are very similar in appearance that attack a wide range of plants, ornamental shrubs and trees and are especially troublesome in sunny sites.

Life Cycle: Eggs are laid in clusters on the undersides of leaves. They are black, cylindrical in shape and stand on end. From these eggs the nymphs emerge, feed on the leaf and deposit black specks of tarry excrement on the undersides of leaves.

There are two generations per year in the prairie provinces. The adults overwinter under loose bark or beneath fallen leaves. The first generation adults emerge in midsummer while the second generation completes its development by early fall.

Damage: Leaves will develop a tiny, yellow-speckled or mottled appearance on the top side of the leaf. This is caused by the insect sucking sap from the undersides of the leaves. Lace bug damage often resembles damage of the leafhopper or spider mite.

As feeding continues the upper leaf surface may show autumn colours close to the main vein, become brown and leathery and fall prematurely, especially in dry weather, the underside of the leaves will have the tarry excrement. Lace bug damage is usually not critical and under normal circumstances, will not cause any long term problems to the host plant, although the discoloration and tarry material are not pleasing in ornamental plantings.

Control: Control, when necessary should be applied early, before too much damage has occurred. Repeated use of soap sprays, (such as 1 tsp. dish detergent/ gal. of water) may be used as well as one of the many Ortho products: Orthene Systemic Insect Control, Isotox Insect Killer, Fruit & Vegetable Insect Control, Rose & Floral Dust, Volck Oil Spray. Products containing Diazinon or Sevin also work on the Lace bugs. Whatever product you choose, carefully check to see that your plant is listed on the product label. Reinfestation may occur from infested plants in neighbouring gardens so check your plants periodically for these insects and repeat the spray if necessary, using the label as your guide.

REFERENCES:

An Introduction to the Study of: INSECTS, by Borror, Triplehorn & Johnson; 6th Ed.; Saunders College Publishing; 1989.

Rodales's All-New Encyclopedia of ORGANIC GARDENING, by Rodale Press Inc.; 1992.

The Ortho Problem Solver; 2nd Ed.; Edited by Michael D. Smith; 1984.

Tree and Shrub Insects of the Prairie Provinces, by W.G.H. Ives & H.R. Wong; Northern Forest Service; 1988.

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Sustainable horticultural information, offered free of charge to the public with the support of the University of Saskatchewan Extension Division, the Department of Plant Sciences and the Provincial Government.