Lace Bugs
Contact: Eric Day, Manager, Insect Identification Laboratory
ENTOMOLOGY PUBLICATION 444-212, August 1996
Lace Bugs
Hosts
Azalea, rhododendron, sycamore, broad-leaved evergreens, and many
deciduous trees and shrubs.
Description of Damage
Lace bug damage is first noticed as yellow spots on the upper
leaf surfaces of affected plants. Lace bugs actually feed on the
undersides of leaves with their piercing-sucking mouthparts, but
because they kill surrounding cells as they feed, they cause the
yellow spots to appear on upper sides of the leaves. The first
yellow spots that appear are very similar to mite damage, but the
spots made by lace bugs are much larger. When feeding damage
becomes severe, the leaves take on a gray blotched appearance or
can turn completely brown. As lace bugs feed they produce brown
varnish-like droppings that spot the underside of the leaves.
These droppings further distinguish lace bug damage from mite
damage. When large numbers of lace bugs are present cast skins
can be found attached to the leaves.
Identification
Adult lace bugs are about 3 to 6 mm (1/8"- 1/4") long with a
netlike pattern on the wings. In addition, the wings are dotted
with brown and black. The immature stages, called nymphs, are
similar except they are smaller and often have spines. The eggs,
although small, are easily distinguished by their elongate and
cylindrical shape. They resemble small black smoke stacks
attached to the undersides of the leaf. Lace bugs are in the
order Hemiptera, family, Tingidae.
Life Cycle
On deciduous plants, adult lace bugs overwinter in protective
places on the host, such as bark crevices and branch crotches, or
on the ground in leaf litter. They end their hibernation just as
spring growth starts. They attach their eggs to the undersides of
the leaves often along the mid-ribs, sometimes covering them with
a black varnish-like coating. The eggs will stay attached to the
leaves long after they have hatched and can be recognized by
noting if the tops have openings. The nymphs complete their life
cycles quickly and one to several generations can occur in one
season; usually, there are two generations. Some lace bugs can
complete a generation in as few as 30 days. Usually, by the end
of the summer, all life stages can be found on a host.
On broad-leaved evergreens, lace bugs overwinter as eggs on the
undersides of leaves. Eggs hatch in May in Virginia and two or
more generations may occur during the growing season.
Control
Lace bug control requires careful monitoring early in the season.
Control should be applied when insects are found on the foliage,
either on adults on deciduous plants or on groups of nymphs on
broadleaved evergreens. It is very important to spray the
undersides of the leaves because this is where they feed. Check
the Virginia Pest Management Guide for specific control
recommendations.
Some Important Lace Bugs in Virginia
Azalea Lace Bug. Two generations of azalea lace bugs occur in
Virginia per year. The second brood builds up to high populations
in August and September and damage can be severe. In some cases,
the leaves turn completely brown and are heavily spotted with
droppings by the end of the summer. Try to control the first
generation from mid-May to mid- June; two sprays may be
necessary.
Rhododendron Lace Bug. Rhododendrons growing in full sun may have
a yellowish appearance from feeding by rhododendron lace bugs.
Damage is not as pronounced as for azalea lace bugs, but
treatment is sometimes needed. Treat in May or June to control
the first generation.
Sycamore Lace Bug. This is an important pest of sycamore,
especially on street and shade trees. Multiple generations occur
each year and defoliation may occur in severe cases. Treat in
June or when nymphs appear; a second treatment may be needed.
Prepared by Eric Day, Department of Entomology, Virginia
Polytechnic Institute and State University Blacksburg, Virginia
24061-0319.