Azalea Lace Bug Solutions

Azalea lace bugs were first documented in Oregon in 2009, but they were not a huge problem until 2012-13. Lace bugs are now very widespread and most everyone who owns azaleas in Portland (some rhododendrons are affected too) has a lace bug problem. Because of this, azaleas can no longer be considered carefree, inexpensive plants.

Lace bugs suck chlorophyll out of leaves, impairing the plant’s ability to make nutrients from sunlight. Damage from adult azalea lace bugs makes leaves look stippled with yellow or white on top and black or brown spots (bug poo) on the underside of leaves.

Treatment

Begin treatment when nymphs are visible. Start looking for them in early May on the undersides of leaves. Nymphs are up to 1⁄4” long and translucent with bits of yellow-green. If you’re having trouble seeing them, hold leaves up to a light and look for nymph shadows.

Chemical-Free Options

• Eggs are laid along the midrib, inside the leaves (so spraying with dormant oils will not kill eggs).
• Eggs typically begin hatching in early-mid May and hatch over a long period of time. A second generation hatches around late June, early-July.
• Nymphs are the next stage. Treatment during the nymph stage is most effective.
• Adults do 12 times the damage of nymphs. They insert a proboscis (straw) into pores in leaves and suck out the chlorophyll, which is what turns affected leaves white or yellow.
• Treating after you notice damage (once adult lace bugs are active) will not repair the stippled appearance of the leaves.

Insecticides

Insecticides will help control lace bugs, but may also harm beneficial insects and bees. Apply only to non-blooming plants, in early morning or evening when bees are not present.

• Organic and naturally occurring insecticides must have direct contact with insects to be effective.
• Nymphs live on the bottom side of leaves, so use a hose-end or pump sprayer and make sure to coat the undersides of all leaves.
• To be effective, these products will require reapplication several times during hatching season. Always follow all directions on the package.

Listed from least toxic to beneficial insects, bees, pets, and humans to most toxic:

• Oil - while dormant oil does not control eggs, spraying nymphs and adults with horticultural oil is effective.
• Insecticidal Soap - works for nymph and adult stages.
• Pyrethrin - is effective for use on lace bugs but is toxic to beneficial insects and bees and also can be harmful to pets and humans. Use should be limited. Apply to non-blooming plants in early morning or evening when air is still and bees are not present. Keep pets indoors until treated areas and the ground around them have dried. Wear long sleeves, gloves, protective goggles, and a dust mask during application. Never apply in an enclosed space.