If you suspect a lace bug problem in your flower garden, get out your magnifying lens because these garden pests are only about 1/8 inch long. Under magnification, you can see where these bugs get their name: Their transparent wings form a lacy shield over their square-shaped bodies.
In the flower garden, the most likely victims of lace bugs are azalea bushes, particularly those growing in sunny locations. The adult bugs and their larvae feed on azaleas and other flowering plants and shrubs throughout the growing season, using their sharp mouthparts to pierce plant foliage and suck the juices from leaves. Damage from lace bugs is primarily cosmetic and does not seriously harm plants. Typical sigs of damage include:
- Yellow or white stippling on leaves
- Evidence of leaf curl
- Browning of leaves during active growth
- Premature leaf drop
4 Ways to Get Rid of Lace Bugs
These tiny insects do not harm humans and typically are not a problem for indoor plants. In many cases, they can simply be ignored, but you may want to treat for heavy infestations, especially when this becomes a recurring problem on specific plants. With most mild infestations, experts encourage gardeners to tolerate these insects because they do not typically cause significant harm, and control efforts often are detrimental to beneficial insects.
The simplest solution for getting rid of lace bugs is to spray them off of the foliage with a garden hose and sprayer. This washes the nymphs from the leaves, and they fall to the ground and cannot return to the plant. This approach is most effective early in the insects' growing cycle, when most of those present are nymphs. Repeating the treatment periodically throughout the season helps to suppress infestations.
Organic Pesticide Sprays
Despite their imposing shields, lace bugs are susceptible to most organic pesticide sprays. The trick is to apply the sprays thoroughly to the undersides of leaves, where lace bugs feed and reproduce. Use these sprays to kill active lace bug adult and larvae populations:
- Light horticultural oil
- Insect soap
Many predators feed on lace bugs, reducing the need to spray insecticides on your plants. Natural lace bug enemies include:
- Assassin bugs
- Pirate bugs
- Predatory mites
If you want to provide a beneficial bug-friendly habitat to attract these natural predators, do not use insecticide sprays. Insecticides not only kill beneficial insects, they also eliminate the food source of beneficial bugs, forcing them to seek greener pastures.
If lace bug swarms are turning your flowering oasis into a withered graveyard, it might be time to break out some conventional chemical pesticides as a last resort. A benefit of these broad-spectrum sprays is their residual effect, helping to kill multiple generations of lace bugs. The following sprays are effective for killing lace bugs:
- Carbaryl, sold under the brand name Sevin
- Imidacloprid, sold under the brand names Merit and Bayer Advanced Garden Tree & Shrub Insect Control
- Malathion, including products by Ortho, Hi-Yield, and Spectracide
- Pyrethroids, including Bonide Eight Vegetable, Fruit, & Flower Spray; Monterey Bug Buster; and Ortho Bug-B-Gon
Of these conventional sprays, only the imidacloprid is systemic, meaning the plant absorbs the chemical, thus it cannot be washed away in the rain or after watering.
Many commercial pesticides are harmful to bees. To minimize risk, do not spray the plants when they have flowers. Follow all manufacturer recommendations for minimizing exposure to bees.
What Causes Lace Bugs?
Lace bugs appear on vulnerable plants typically in late spring and into early summer. The lace bug life cycle begins when the adult female inserts eggs into the leaves of host plants, typically on the underside and near the midrib of the leaf. Nymphs hatch from the eggs in about two weeks and begin feeding on the leaves. The nymphs mature into adult lace bugs in three to four weeks.
You can identify lace bugs by simply inspecting the undersides of leaves. Adults and developed nymphs (which are wingless and have dark spines on their bodies) are readily visible on leaf surfaces, if you look closely. Another common sign of lace bugs is the presence of shiny brown to black spots on the leaf surface. These are coverings of excrement that female lace bugs place over their eggs for protection (most, but not all, species do this). The spots remain on leaves after the eggs hatch and the nymphs mature into adults.
How to Prevent Lace Bugs
As with all plants, those under stress make the tastiest meal for insect pests. Ensure your plants can shrug off minor lace bug attacks by keeping them healthy. You may as well hang up a neon “Dine Here” sign if you allow your azalea to bake in full sun. Dry soil and an absence of mulch also create conditions that pique the interest of lace bugs. Dappled shade or morning sun, regular irrigation, and a 3-inch layer of organic mulch help to keep plants vigorous and pest-free.
If lace bugs become a perennial problem for specific plant type or plants in certain locations, consider replacing the plants with less susceptible species or moving the plants to a location that is less favorable to lace bugs. If your azaleas are frequently attacked and they get a lot of sun, try moving them to a part-sun location, provided they get enough sun to thrive. There are also azalea cultivars that boast resistance to lace bugs as well as other shrubs known to be resistant, such as hydrangea and daphne.
Lace bugs can overwinter on evergreen plants and emerge in the spring. Eggs survive on leaves, while adults survive under bark, leaf or mulch debris, or other cover for protection. In climates with mild winters, lace bugs can overwinter as eggs, nymphs, and adults. You can help eliminate overwintering bugs by raking up dropped leaves and other debris from beneath susceptible plants. Some experts recommend leaving the soil beneath plants bare (free of mulch) for mid-winter, then mulching (as needed) before spring, using fresh mulch. Be sure the new mulch does not contain leaves from the same family of plants, which may attract lace bugs in the future.
Do Lace Bugs Aattack Trees?
Lace bugs do infest and feed on deciduous trees in some areas. Species known to be susceptible include hackberry, oak, sycamore, walnut, white oak, bur oak, willow, basswood, and London plane tree, among others. As with shrubs, the damage to trees caused by lace bugs is primarily cosmetic and typically is not fatal.
When Should I Treat for Lace Bugs?
In general, treatments for lace bugs are most effective when started during spring and early summer, when the season's first generation of nymphs are developing. Treatment should continue through summer to combat subsequent generations (there may be three or four total, depending on the area). Leaf damage may not be noticeable or significant until late summer. At this time, treatment may not be worthwhile because it will not prevent from much additional damage, and the damage cannot be reversed.
What Are Azalea Lace Bugs?
There are about 140 species of lace bugs in North America. Many of the better-known species have common names derived from the plants a given species targets most, such as azalea lace bugs, sycamore lace bugs, oak lace bugs, and hawthorn lace bugs. Treatment methods generally are not specific to species, but your local extension may have special tips for treating the most common lace bugs in your area.