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Scouting Watch

June 16, 2004

Lacebugs have been found on linden at the Morton Arboretum in northeastern Illinois. Lacebugs are typically 1/8 inch long and flattened. They appear whitish, due to the first pair of wings, which appear lacelike under magnification. Nymphs are blackish to brownish, depending on the species. Different species of lacebugs are common in Illinois on sycamore, linden, hackberry, and oak. Typical damage consists of whitish stippling on the upper side of the leaf. The bugs are typically located along the veins on the underside of leaves. The leaf underside has black, tarlike spots of fecal material that look like pepper. On most trees, damage is slight enough that control is not needed. On hackberry, lacebug can cause the leaves to turn yellow and fall off. If needed, pyrethroid and other labeled insecticides are effective.

Oak sawfly damage has also been reported at the Morton Arboretum on pin oak. Larvae appear initially as yellowish slugs on the leaves, causing window-feeding. Older larvae lose their slime and appear greenish. These older larvae may also feed on leaf margins, causing defoliation in heavy infestations. They are controlled by carbaryl (Sevin) and labeled pyrethroids.

Author: Phil Nixon Morton Arboretum


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