Gargaphia solani Heidemann Hemiptera Tingidae

Natural history

Distribution. Eggplant lace bug occurs widely in the eastern United States north to about New Hamp shire and Iowa, and west to Kansas and Arizona, but it is not common in the Gulf Coast area. There are occasional reports from outside this range, including from Canada, but it is infrequently abundant in such areas. The range of eggplant lace bug also extends into Mexico. This appears to be a native insect.

Host Plants. As its common name suggests, this insect affects principally eggplant, though it sometimes affects potato and perhaps tomato. Not surprisingly, it is commonly found on weeds in the plant family Solanaceae such as horsenettle, Solanum carolinense, and silverleaf nightshade, S. elaeagnifolium. Eggplant lace bug occasionally is reported from hosts other than Solanaceae, including Compositae, Legu-minosae, and Malvaceae.

Natural Enemies. Several common predators have been observed to attack eggplant lace bug, among them the lady beetles Hippodamia convergens Guerin-Meneville and Coleomegilla maculata De Geer (Coleoptera: Coccinellidae); the spined soldier bug, Podisus maculiventris (Hemiptera: Pentatomidae); the insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae); and various spiders.

Life Cycle and Description. In Virginia the complete life cycle takes about 20 days, and these lace bugs are active from May to November. Adults overwinter, often in clumps of grass but sometimes under bark. The number of generations is estimated at 6-8 per year, but overlap so completely that they are hard to distinguish.

  1. The eggs are deposited on the lower surface of leaves in clusters containing over 100 eggs. The eggs are attached on end, and are not erect, but rather tilted at different angles. They are about 0.37 mm long and 0.18 mm wide. They are brown basally and greenish apically. The tips of the eggs are recessed and surrounded by a delicate, lace-like border. The female may require 4-5 days to complete the egg cluster, depositing 15-60 eggs at each oviposition. At completion of egg laying, a sticky secretion is spread over the cluster, and the female tends the eggs, leaving only to feed for brief intervals. The incubation period is 5-8 days.
  2. Nymphs remain clustered as they feed and grow. There are five instars, each with a duration of approximately two days. The first instar is light-yellow, with pink eyes, and antennae are about as long as the body. This instar measures 0.3-0.4 mm long. At the molt to the second instar, which measures about 0.8 mm long, the nymph acquires large spines laterally on the thorax and abdomen. The third instar is about the same length as the preceding stage, but is wider, bears spines dorsally, and displays evidence of wing pads. The fourth instar measures about 1.5 mm long, the thorax is greatly expanded laterally, the entire body is covered with spines, and the wing pads extend to about the second abdominal segment. The fifth instar is about 2.2 mm long, and like the preceding instars, yellowish in color. This stage also is adorned with spiny processes, most of which are brown in color.
  3. The adult eggplant lace bug is rather flat in general form, and mostly dark brown, though the legs are yellow. The front wings are distinctively lacy, with the basal cells more densely packed. The thorax is pronounced, flaring laterally but also extending posteriorly. The antennae are nearly as long as the body, and thickened apically. The adult measures about 4 mm long and 2 mm wide. Adults have a relatively brief period of oviposition, usually 4-5 days, after which they turn their attention to brood care.

Eggplant lace bug adults display complex social interactions, including maternal behavior. For example, the female remains with the eggs and nymphs as they develop. As nymphs deplete the food and become restless, the adult leads them to a new feeding site. Nymphs respond to an alarm pheromone that is released when the bugs are crushed by dispersing quickly, only to reassemble at another location, accompanied by the adult. The alarm pheromone was described by Aldrich et al. (1991a). The adults use wing fanning to deter predation, and also to communicate with nymphs. There is some evidence for an aggregation pheromone (Kearns and Yamamoto, 1981). Interestingly, females frequently deposit their eggs within egg clusters of other females. This relegates the recipient female to surrogate mother status, allowing the donor female to continue to produce more eggs without the responsibility for care of her offspring (Tallamy, 1985).

An excellent treatment of eggplant lace bug biology was given by Fink (1915), with supplementary information provided by Bailey (1951). Eggplant lace bug

Tingidae Key
Adult eggplant lace bug.

was included in keys to the Hemiptera of Missouri (Froeschner, 1944) and the lace bugs of North Carolina (Horn et al., 1979).

Damage

The adults and nymphs suck sap from the leaves of host plants. The first symptom of injury is large discolored blotches or patches, usually circular in shape. This reflects the feeding by the adult, and perhaps the very young nymphs, in the vicinity of the egg cluster. Later, as the nymphs disperse away from the egg cluster, the discoloration spreads until the entire leaf is involved, turning yellow and dry. Often every leaf of an infested plant is discolored as the insects move from leaf to leaf. The adults disperse from plant to plant.

Management

Although lace bugs are not often serious pests, they occasionally reach damaging levels. They are readily suppressed with insecticides applied to the foliage, but care must be taken to attain thorough coverage of the plant because these insects are found on the lower surfaces of the leaves.

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