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 of an inch long. Under magnification, you can see where these bugs got their name: their transparent wings form a lacy shield over their square-shaped bodies.
Identify Lace Bug Damage
In the flower garden, the most likely victims of lace bugs are azalea bushes. Lace bugs especially seek out azaleas growing in sunny spots. Lace 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. If your flowers are infested with lace bugs, you might notice:
- Yellow stippling on leaves
- White stippling on leaves
- Evidence of leaf curl
- Browning of leaves during active growth
- Premature leaf drop
Lace Bug Life Cycle
Like many bugs, lace bugs begin their life cycle as larvae. The female lace bug inserts the eggs into the leaves of host plants, so a food source is available to newly hatched larvae. The larvae are tiny and difficult to see, but they are usually present and feeding under leaves along with their parents. After about six weeks, the larvae mature into adult lace bugs, which can spawn several more generations of pests that season.
Organic Sprays for Lace Bug Control
In spite of their imposing shields, lace bugs are susceptible to most organic 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
Cultural Control of 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 “dine here” neon sign if you allow your azalea, a woodland shrub, 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 keep plants vigorous and pest-free.
Beneficial Insects That Kill Lace Bugs
Many predators feed on lace bugs, reducing your need to spray insecticides on your flowering 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, eliminate the use of insecticide sprays. Insecticides not only kill beneficial insects, but they eliminate the food source of beneficial bugs, forcing them to seek greener pastures.
Conventional Pesticides to Control Lace Bugs
If lace bug swarms are turning your flowering oasis into a withered graveyard, it might be time to break out some conventional chemical pesticides. A benefit of these broad-spectrum sprays is their residual effect, helping to kill multiple generations of lace bugs. Use any of these sprays to kill lace bugs:
- Carbaryl, sold under the brand name Sevin
- Imidacloprid, see below
- Malathion, marketed 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 takes up the chemical, making it rainproof. Homeowners can shop for imidacloprid under the brand name Merit or Bayer Advanced Garden Tree & Shrub Insect Control.