Azalea Lace Bug
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DESCRIPTION
Adult- The adult is 3 mm long and 1.5 mm wide, dark in color with a hoodlike covering on
the head and netted, lacy, off-white wings with brown or black markings. The wings are
folded flat over the abdomen. The legs and antennae are light brown.
Eggs- The small (0.8 by 0.4 mm), smooth, white egg is oval with the neck to one side. It is
usually deposited in the tissue of the leaf along the midrib or a large vein. In some cultivars,
the eggs are deposited along the leaf margins. The eggs are inserted with the neck
slightly above the leaf surface, and they are covered with a "flyspeck" of blackish frass.
Nymph- Found almost exclusively on the underside of the leaf, the nymph is colorless at
birth but soon turns black and spiny. Nymphs pass through five nymphal instars before
molting into the adult stage. They grow from 0.4 to 1.8 mm. Wingpads develop after the
fourth instar.
Fig. 59. Azalea lace bug, Stephanitis pyrioides (Scott), Tingidae, HEMIPTERA
Zoom Fig. 59: Full view, Azalea lace bug. A, Adult. B,egg. C, D, E, nymphs.
BIOLOGY
Distribution- In the United States, the azalea lace bug occurs from New York to
Massachusetts southward to Florida and west to Texas.
Host Plants- The evergreen azalea cultivars are the preferred hosts of azalea lace bugs,
although deciduous cultivars may be attacked as well as mountain laurel and rhododendrons.
Damage- Injury is caused by the adults and nymphs as they feed through piercing,
sucking mouthparts. They extract the liquid contents of the leaf tissue through the
undersurface. The upper surface of infested leaves become stippled or blanched,
and in severe infestations, leaves gradually turn gray to white and eventually may
dry up and fall. The undersurface becomes rust colored and covered with dark spots
("varnish spots") of tarlike excrement. Cast skins of nymphs are often observed on
the undersurfaces. Damage usually begins on the lower leaves and moves upward.
Life History- Since its introduction from Japan in the 1920s, the azalea lace bug has
become the most serious pest of azaleas. Females lay groups of eggs along the
midribs of leaves, along the larger veins (and along the margins of some cultivars)
on the undersurface. Females deposit eggs over a 2to 3-month period. The eggs
hatch in about 2 weeks and the nymphs develop through five stages. Newly hatched
nymphs are colorless but gradually turn black. Depending on temperatures, nymphs
take 10 to 21 days to develop into adults. With such a long egg-laying period, it is
common to see all life stages at any time during the growing season. Outdoors
there are four generations produced each year. The egg is the usual overwintering
stage, although in mild winters adults survive to lay eggs the following spring. In the
south eggs begin hatching in late February producing dense populations in March,
April, and May. A second generation occurs in July, August, or September, depending on location. This generation lays the
overwintering eggs in October. In the greenhouse, azalea lace bugs can appear in
large numbers in early spring and occur throughout the spring, summer, and into the fall.
CONTROL
Insecticides may be required for effective control. A predaceous plant bug,
Stethoconus japonicus Schumacher, from Maryland and New York has been
reported to feed voraciously on azalea lace bugs in landscapes. Perhaps some time
in the near future Stethoconus japonicus may contribute to effective management of
azalea lace bugs throughout the southern United States.
Control can be accomplished if the life cycles are broken early. Sprays should be timed
for the first appearance of adults or nymphs in the spring just after the blooms have
faded. Two applications or more may be needed because of the extended oviposition
time. Systemic insecticides are most effective, and one application may suffice.
Nonsystemic insecticides require thorough coverage of the undersurfaces of the
foliage, and several applications may be required for complete control. Once damage
has occurred, control of the lace bugs will not correct their injury. For specific chemical
controls, see the current Cooperative Extension publications on ornamental plant pests
or contact your local county Extension agent.
Zoom Fig. 59: Full view, Azalea lace bug. A, Adult. B,egg. C, D, E, nymphs.