Green sharpshooter

grnshrp2Distribution and habitats: The green sharpshooter (Draeculacephala minerva) is considered to be one of two important species of insect vectors for Pierce’s disease and alfalfa dwarf diseases in the Central Valley of California. It also occurs in coastal areas in grasses and sedges along streams. Although it has been found on many species of herbaceous plants, it strongly prefers to feed and reproduce on grasses. It is most common on water grass (Echinochloa cruz-galli), fescues, perennial rye grass and Bermuda grass. Its most common habitats are ditch banks, weedy hay fields and permanent irrigated pastures, anywhere that its preferred grasses continue to grow throughout the year. For this reason it is common in orchard or vineyard cover crops only when there are attractive plants in the cover crop at all times of the year. It is only rarely seen feeding on grape. Its role as a Pierce’s disease vector is based on the consistent occurrence of its breeding habitats near vineyards.

Life cycle: There are usually three generations per year in California. Beginning in February and March, females insert eggs into the leaves of winter annual or perennial grasses. Nymphs emerge from late February through March. Second generation eggs are laid beginning in April or early May. Nymphs from the second generation reach maturity during the latter part of June through July, during which time third generation eggs are deposited. Adults stop reproducing in the autumn and begin to lay eggs in grasses as soon as temperatures are warm enough, usually in January or February. Adult coloration can vary from bright green through dull brown during winter, whereas during late spring and summer, the upper surface of adult green sharpshooters is a bright grass green. In some areas, most adult green sharpshooters are brown during the fall and winter.

Control: Spatial patterns of the occurrence of Pierce’s disease in vineyards shows that most disease is spread by green and/or red-headed sharpshooters flying into vineyards from nearby (usually adjacent) vector breeding areas such as irrigated pastures or ditch banks. Grasses within vineyards do not seem to be a major problem in spreading Pierce’s disease if the grasses die out or are removed by cultivation in fall or winter. Bermuda grass are breeding hosts of the green and the red-headed sharpshooters, and may contribute to the spread of Pierce’s disease if they harbor overwintering adults within the vineyard.

For more information: You may find more details on the green sharpshooter and its relation to Pierce’s disease, in the reference section by referring to scientific papers by DeLong and Severin 1949; Freitag and Frazier, 1946; Goodwin and Purcell, 1992;Hewitt et al., 1942; 1949; Purcell and Frazier, 1985.