The Q&A Archives: What are lace bugs?

Question: A lawn care service told me my azelea bush and my rhododendron bushes have lace bugs on them. What are they and how should I treat them to get rid of them?

Answer: Lace bugs are common in landscapes and usually detected when their damage to the leaves of host plants becomes evident. The nymphs and adults live on the lower surface of leaves and suck juices through slender, piercing mouthparts. This produces yellow or whitish spots on the upper surface of the leaf. As the insects feed, they deposit a hard, varnish-like excrement onto the leaf surface. These are called tar spots or resin spots.

Once the damage is noticed, the adults and nymphs can be found by turning over affected leaves. Adult lace bugs are about 1/8 inch long by 1/16 inch wide. They are somewhat rectangular in outline. The nymphs are oval in outline and often covered with long spines. Most of the lace bugs move rather slowly when disturbed but the hackberry lace bugs tend to drop from the leaves that are touched.

The azalea lace bug overwinters in the egg stage. The eggs are partially inserted into the leaf tissues along the midvein and are covered with the resin-like excrement of the female. The nymphs hatch in the spring, usually mid-May, after the danger of frost is over. They feed in small groups on the under surface of leaves and molt five times before becoming adults. The adults mate and lay eggs for a second generation by mid to late-July. Often there is a third generation in the late summer and early fall. The rhododendron lace bugs have similar life cycles.

You can control these pests by rinsing them off the plants. Use a hard jet of water from a hose to dislodge the young nymphs as they hatch in the spring. The tiny nymphs often die before they can find their way back to suitable leaves.

You can also encourage natural predators such as green lacewings, mites and assassin bugs by not using chemicals in your garden. Once the population of bad bugs gets large enough, a population of benefical insects usually arrive to feast on the bad guys.

Or, you can use chemicals to control the pests. Insecticidal soaps are useful if contact with the nymphs is made. Be sure to cover the underside of the leaves where the nymphs are feeding. Additional applications may be needed to control nymphs hatching out of eggs laid late or if re-infestations occur from surrounding landscapes.

Hope this answers all your questions!

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