Q: I feel your answer to the lady asking about browning leaves on the azaleas on the north side of her house should have included some information on lace bugs, which are very common on azaleas and typically cause the damage she describes.

A: You are right, I should have mentioned the lace bugs. Sometimes I run out of room in an article, and sometimes I just forget about an obvious part of an answer. This time, it's the latter. Although, in my defense, lace bugs do prefer sunny locations over shady ones, and the north side of the house is the shady side.

There are many species of lace bugs that occur on many kinds of ornamental plants. They are only about 1/8-inch long. The top of their bodies and their wings have numerous clear cells that give a lacelike appearance. The bugs are smaller during the wingless nymph stage and usually dark colored with spines. Adults and nymphs occur together in groups on the underside of leaves, where they suck the sap. As they remove the green chlorophyll, the leaves turn brown.

Lace bug feeding is usually not a serious threat to plant health or survival. High populations of lace bugs may cause the leaves to drop and the plant growth to reduce. But a persistence of large populations for several years can stunt or kill a plant.

Lace bugs have several generations a year. They can overwinter as eggs in leaves on evergreen plants, and as adults in protected locations, such as under bark and fallen leaves. In areas with mild winters, all life stages can be present throughout the year on evergreen hosts.

If lace bugs are present, they may be controlled by pouring a forceful stream of water on the undersides of leaves beginning early in the spring or summer, when nymphs are the predominant life stage. Like any bug control, repeat the spray as necessary.

Natural enemies of lace bugs include parasitic wasps, lacewing larvae, lady beetles and mites. These beneficial species may not appear in sufficient numbers until the lace bugs become abundant. And it is essential to a healthy landscape to not harm the beneficial insects. If applying pesticides, choose nonpersistent contact insecticides to minimize the adverse effects on beneficial predators and parasites.

When properly applied, almost any contact insecticide will control lace bugs. Contact insecticides that do not leave persistent, toxic residues include insecticidal soap, neem oil and pyrethrin products. These insecticides are not very toxic for people and pets and have relatively little adverse impact on beneficial pollinators.

Systemic insecticides are also available for use against lace bugs. When properly applied, one application may provide control all season long. Do not apply systemic insecticides to plants during flowering or shortly before. Wait until after the plants have completed their seasonal flowering, unless the product directions say otherwise. With soil applications, wait until nearby plants have also completed flowering when possible, as their roots may take up some of the soil-applied insecticide.

Email questions to Jeff Rugg at [email protected]. To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.