What’s on my Pieris? The Andromeda Lacebug (Stephanitis takeyai)!

The common name ‘lacebug’ is often confused with the common name ‘lacewing’, and those that promote natural insect predators in their yards know what a huge misnomer this is. The lacewing is a beneficial predator of many garden pests, one being the lacebug! The Andromeda lacebug is a relatively new pest; in British Columbia, it is still on the ‘introduced list’. Under a dissecting microscope, or even a 10 powered hand-lens, this insect looks fantastic. True to their name the wings take on a ‘lacey’ appearance.

Host Plants:
Pieris, formerly Andromeda, is a group of three species, the most common being the Japanese pieris (Pieris japonica) in our Pacific Northwest area, and it is extremely susceptible to this pest. Injury to P. japonica can be severe especially when the host grows in full sun. Mountain pieris (Pieris floribunda) is native to North America and is highly resistant to lacebug attack and should be utilized in place of P. japonica wherever possible but from a horticultural point of view, this alternative plant is less showy and not as desirable as Japanese pieris. Himalaya pieris (Pieris formosa) has a nice shape with large leaves but needs an even, cool climate, as found here in Washington. This critter may also attack rhododendrons and azaleas, and is sometimes also found on Leucothoe.

Biology and Symptoms:

Lower leaf surface nymphs & adult with fecal drops

These insects belong in the order Hemiptera, which have piercing-sucking mouthparts. Lacebugs over-winter as eggs embedded within leaf tissue. The ovipositional sites are often covered with shiny, dark, varnish-like drops of excrement. Hatching generally occurs around the middle-to-end of March. Feeding commences immediately, after which they leave behind unsightly brown fecal drops. Lacebugs undergo incomplete metamorphosis, so the immature stages (nymphs) look similar to the adults with some morphological differences, the main being the lack of wings. Both nymphs and adults feed on the undersurface of leaves and leaf upper surfaces develop a severe yellow stippling or mottled appearance.

On a healthy plant this damage seems to be mainly cosmetic, and plant health is largely unaffected. But for plants not in their proper place, a high lacebug infestation can reduce the attractiveness of the foliage by causing chlorosis. At its severest, this pest can cause premature defoliation and weaken the plant.

Management Strategies:

Stippling damage as seen from top of leaf

Japanese pieris growing in full sun will be severely attacked; avoid such plantings and use Mountain pieris whenever possible. Wash off pests with water spray. Lacebugs are susceptible to most insecticides, but it is prudent to use integrated pest management strategies; early detection by weekly monitoring in early spring can negate the use of insecticides. In early spring, start to inspect trees for lacebug and other pests and monitor weekly throughout the summer until late summer. Make sure to look for the presence of beneficial predators, such as ladybird beetles, lacewings and several species of mirid plant bugs. Mirid plant bugs are about the same size as adult lacebugs, but are narrower and coloured differently. There is also a tiny parasitic wasp known to parasitize eggs of andromeda lacebugs. When this wasp completes its development, it exits through a round hole it chews at one end of the lacebug egg. Examine plants with your hand-lens for evidence of parasitoid exit holes in lacebug eggs to confirm the presence of these minute stingless wasps in the landscape.