Aster Leafhopper

Several species of leafhoppers feed on rice plants in California, but the aster leafhopper is the only one known to be of economic importance. The adults are about 0.125 inch (3 mm) long, with transparent wings that are strongly veined and body background colors of gray and black. The nymphs have small wing pads in their last instar and range in color from yellow to dark green.

Leafhoppers usually overwinter in the egg stage, although nymphs and adults may be found all year. The leafhopper inserts its eggs into tender plant tissues. Wingless nymphs hatch from the eggs and go through four to five molts before reaching maturity. Leafhoppers may complete up to six generations between spring and fall.

Although leafhoppers can be present in fields during most of the growing season, the largest numbers usually occur from early July through mid-August. Leafhoppers feed on rice plants by sucking plant fluids through their long, piercing mouthparts.

Although they are not known to be a vector of any rice pathogens in California, leafhoppers may occasionally occur in sufficient numbers to cause damage by their feeding. Injury caused by leafhoppers includes stippling, yellowing, and drying leaves. Leafhoppers prefer senescing leaves, and symptoms usually occur on older leaves first. Because leafhoppers are very mobile (nymphs jump and adults fly), an infestation generally appears throughout a field.

High numbers of this pest are associated with fields heavily infested with broadleaf weeds and sedges, and with fields fertilized with excess nitrogen. Control weeds and monitor during the summer to determine the need for insecticide application. Use nitrogen rates that optimize yields. Predation can provide significant reduction of leafhopper numbers.

Small plot studies in rice paddies have shown a wolf spider, Pardosa ramulosa, to significantly reduce numbers of the aster leafhopper. For more information on practices that protect natural enemies, see Protecting Natural Enemies and Pollinators.

An early and effective weed control program is an important way to prevent economically damaging numbers of leafhoppers from building on weeds and then moving to rice. Use appropriate nitrogen rates and assess the need of a nitrogen top dress.

Use biological and cultural controls in an organically certified crop.

Observe fields weekly from July through August for leafhoppers and their damage. Leaf yellowing and stippling can be associated with other stresses, so always check for the presence of leafhoppers. Leafhopper adults, nymphs, and molted skins are apparent when walking slowly through a field. Always inspect fields carefully after broadleaf herbicide treatment; the killing of broadleaf weeds may cause the leafhoppers to move from the dying weeds to the rice plants. Although there are no available treatment thresholds, a good rule of thumb is to consider insecticide application when young upper leaves become infested and begin to dry.