bugs are common pests of azalea, rhododendron, sycamore, broad-leaved
evergreens and many deciduous trees and shrubs. The adults have highly
ornamented wings and a hood-like structure covering the head. The
entire surface of the insect is covered with veins that look like
bugs are about 3 to 6 mm (1/8 to 1/4 inch) long with a netlike pattern
on the wings, which are dotted with brown and black. The immature
stages, or 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 can
be divided into two groups - those that attack deciduous trees and
shrubs and those that attack evergreen shrubs. Lace bugs which attack
deciduous plants spend the winter in the adult stage by hibernating
on the plant under bark or near the plant in leaf litter. Lace bugs
which attack evergreens overwinter in the egg stage attached to
lace bug is one species which attacks deciduous plants. The adults
hibernate under loose bark of their host plants as well as among
leaf litter. They become active in early to mid-May and return to
the new leaves. The females soon begin to lay eggs along the larger
veins on the lower leaf surface. The females may lay eggs for a
considerable time, often extending into June. The eggs hatch in
a couple of weeks, and the nymphs cluster together and feed. Each
nymph sheds its skin (molts) five times before the adult stage is
reached. Growth to the adult stage usually takes three to four weeks.
Peak numbers of this pest are usually present in July. Only one
generation occurs per year. Related
species of lace bugs such as the oak, sycamore and hackberry lace
bugs have two and occasionally three generations in a summer.
lace bug is an example of a lace bug which attacks evergreens. The
azalea lace bug overwinters in the egg stage. The eggs are partially
inserted into the leaf tissues along the midvein and are covered
with the resin-like excrement of the female. The nymphs hatch in
the spring, usually mid-May. They feed in small groups on the under
surface of leaves and molt five times before becoming adults. The
adults mate and lay eggs for a second generation by mid to late-July.
Often there is a third generation in the late summer and early fall.
The andromeda and rhododendron lace bugs have similar life cycles.
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 the
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.
attract lace bugs should be monitored early in order to determine
if an infestation is building. Elimination of the first generation
of lace bugs is necessary if visual damage is to be avoided. Existing
spotting and yellowing of leaves will not disappear once the lace
bugs have been controlled.
Most lace bug problems occur in bright, sunny areas. Plant lace
bug-susceptible plants in shady areas of the landscape. The azalea
and rhododendron lace bugs are rarely a problem when their host
plants are in a shaded understory. Syringing can also be an effective
control method. Use a hard jet of water from a hose to dislodge
the young nymphs as they hatch in the spring. The tiny nymphs often
die before they can find their way back to suitable leaves.
Encouraging the natural predators of lace bugs is important. Green
lacewings, mites and assassin bugs all attack lace bugs and will
generally keep a lace bug population in check, especially if host
plants are sited properly. However, these predators often arrive
after considerable damage has occurred. In order to conserve these
beneficial natural predators, use syringing or insecticidal soaps
or oils instead of standard insecticides.
Insecticidal soaps and horticultural oils are useful if they
contact the nymphs directly. Be sure to cover the underside of the
leaves where the nymphs are feeding. Additional applications may
be needed to control nymphs hatching out of late-laid eggs or if
re-infestations occur from surrounding landscapes. Several over-the-counter
insecticides are effective in lacebug control, but soaps and oils
are usually adequate. Be sure to check a product's label, as not
all lace bugs or host plants are listed on each label. Make applications
as soon as the eggs hatch in the spring, usually mid to late-May.
Monitor the plants and repeat applications if re-infestations occur.
If plants are repeatedly attacked, consider moving them into the
from the Virginia Cooperative Extension and the Ohio State Cooperative
Photo from the Clemson University Extension.