Damage typically appears first on older leaves and appears later on new growth.
The presence of a lace bug infestation can be determined by examining the underside of the leaves. Look for the actual insects (up to 10 lacebugs may be present on one leaf). As they feed, lacebugs deposit black, varnish-like fecal
spots that stick to the leaf. sign that lacebugs are (or
These spots are were) present.
Lace bug feeding not only ruins the appearance of the host plant, but reduces its vitality. Shrubs may die if severe injury continues for several years and the plant is also under environmental stress. Research shows that host plants are more susceptible to lacebugs if planted in full sun and subject to drought stress. For example, azaleas planted in direct afternoon sun are ap- proximately twice as likely to be infested by lace bugs than plants growing in the shade.
Heavy lace bug feeding on the foliage of trees causes stippling damage along leaf veins and premature leaf drop.
Lace bugs overwinter in the egg stage. Eggs are inserted into the midrib, or vein, of the lower leaf surface and are usually covered with fecal mate- rial. Hatching occurs from late April until early June, depending on the lace bug species. The young nymphs feed and pass through five stages, or molts, before becoming adults in about 3 weeks. Adults lay eggs over an extended period, so it is possible to find all lace bug stages together on the underside of leaves at the same time. An entire generation can occur within 4-6 weeks, and more rapidly during hot weather. One to three generations are produced throughout the sum- mer, depending on the weather (Table 1). Eggs or adults may overwinter, depending on the lace bug species.
Monitoring and Cultural Control
Examine plants carefully, beginning at the ap- proximate time of egg hatch (Table 1) and continu-
ing throughout the summer. Look on the under- side of foliage for fecal spots, empty, shed “skins” from molted nymphs; eggs; or live lace bugs.
Remember that healthy plants, free from drought stress, are less susceptible to lace bug attack. Monitor plants in full sun more closely. Pay close attention to plants in areas of reflected light or heat, such as next to a building or sidewalk. Keep plants watered during dry periods, and mulch lightly to conserve moisture. Consider relocating the plant if lace bugs are a continual problem, or consider planting a resistant variety (Table 2) to avoid a lace bug attack entirely.
Azaleas Resistant to Lacebug Attack (in order of decreasing resistance)*
Delaware Valley White
Mrs. G.G. Gerbing
*Research by Dr. Peter Schultz, Virginia Beach Experiment Station, Virginia Polytechnic Institute.
Control when live lace bugs are first observed in order to prevent foliar damage.
1. Biological Control
Several biological control agents, or beneficial insects, have been reported. Naturally occurring predators include the azalea plant bug, tree crick- ets, earwigs, minute pirate bugs, and spiders.