BEET LEAFHOPPER

A, Life stages: a, adult; b, nearly mature nymph; c, young nymph (all about eight times natural size). B. C. and D show the effect of curly top disease on tomato, sugar beet, and bean, respectively.

BEET LEAFHOPPER

The beet leafhopper, commonly called the whitefly in the West, is the only known carrier of curly top, a destructive virus disease of sugar beets, beets, beans, tomatoes, cantaloups, some ornamental flowering plants, many weeds, and other crops. The insect occurs in the arid and semiarid regions of the western United States, northern Mexico, and southwestern Canada.

The beet leafhopper passes the winter in the adult stage, chiefly in uncultivated and overgrazed areas where there are mustards or other suitable host plants. The insects are active and feed during the winter whenever the temperature permits. The female usually begins to lay eggs about the time the overwintering host plants begin their spring growth. The eggs are laid inside the tissues of the leaves and stems of plants. They hatch in 5 to 40 days, depending on the temperature. The young leafhoppers, or nymphs, emerge from the eggs and immediately begin to feed by inserting their beaks into the plant tissue and sucking the juices. As they grow, they shed their skins five times, becoming larger after each molt. After the fifth molt, they become adults and have wings. Development of the insect from egg to adult takes from 1 to 2 months. The generations overlap considerably. All stages may be found in the same breeding area at the same time in the summer. In the northern areas three generations are produced each season. In the warmer regions in Arizona and California, five or more generations may develop.

Control: Reducing curly-top infection in susceptible crops by controlling its carrier, the beet leafhopper, with insecticides is a difficult problem, because there might be continuous reinfestation. Applications of DDT will reduce beet leafhopper numbers but will not prevent the feeding of all leafhoppers that reinfest the fields. Weekly applications of 1 pound of actual DDT per acre for 3 or 4 weeks during the spring movement have reduced curly-top infection.

Chemical control of the beet leafhopper in weed-host areas that contribute large populations to the cultivated areas has proved practical. An oil solution or an emulsion containing DDT is applied as a spray from aircraft or mist blowers to the large breeding areas. The spray should be applied in the spring at the rate of 1 pound of DDT in 2 gallons of spray per acre before the leafhoppers begin to move to cultivated areas.

The control of weed-host plants of the leafhopper in the major breeding areas by proper land management is practicable. The replacement of weed hosts by perennial grasses that are not breeding hosts of this leafhopper may best be accomplished by reseeding the abandoned and burned areas; if native perennial grasses are still present, protection against overgrazing will accomplish the same purpose.