July 17, 2010 Transitory Insect Invasion—Leafhoppers Originally published in the Contra Costa Times by Emma Connery, UC Master Gardener Program Coordinator That flying and hopping invasion of little

brownish insects is transitory.

Q: Help! There are some little brownish feed on agricultural crops and weeds. In SUMMARY insects that are appearing on the outside California the largest over-wintering and of my windows, on the ceiling of my spring breeding grounds are in the For the home gardener, porch, and even inside my kitchen. They eastern foothills of the Coastal Range, leafhoppers are seem to be attracted to light. They fly but while the summer breeding grounds are primarily a nuisance they also hop, are less than ¼ inch long, in the west side of the San Joaquin pest. The transitory and some are green and some are brownish Valley. The migratory generation, the minor problems they black. What are they and is there one we are seeing right now, is the cause don’t warrant the something I can or should do to control generation traveling from the spring to use of pesticides. them? the summer breeding grounds, and they are capable of flying several hundred A: The insects are Leafhoppers miles. Beet leafhopper populations are (Homoptera: Cicadellidae). Here in the greatest in those years with good California we have more than 200 rainfall. different species of leafhoppers. It often takes a specialist to identify between Nuisance Pests: species but I suspect the species you are All leafhoppers are plant feeders and seeing is the Beet Leafhopper (Circulifer must have green vegetation on which to tenellus). Over-wintering beet feed. They have a piercing-sucking leafhopper adult females lay eggs in the mouthpart which they use to pierce spring on their preferred host plants, plant material, puncturing leaf cells and rangeland weeds, such as mustards, sucking out the contents. The destroyed peppergrass and filaree. The new leaf cells become visible as tiny white generation of leafhoppers matures in spots. Continued feeding results in the May and June, just as their host plants accumulation of many destroyed cells mature and dry. The leafhoppers then and many white spots. Leafhoppers fly in swarms to their summer host occur on almost all types of plants, plants in the interior valley where they including forest, shade, and orchard

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ccmg.ucanr.edu July 17, 2010: Leafhopper Invasion Is Transitory, page 2

trees, shrubs, grasses, and many field North America of beet curly top virus. If “The direct feeding by and garden crops. The food of most it feeds on infected plants during winter species is quite specific, and their habitat and spring it can then carry the disease beet leafhopper is therefore well defined. They to the agricultural areas in the interior absolutely do not feed on people or pets valley. If you have a home garden and causes relatively so you have nothing to worry about in are growing any of the crops listed above that department. If they have entered then there is a chance that the minor plant damage your home or are a nuisance at leafhoppers may feed on your crops entryways simply vacuum them up. during their migratory path and in doing but its pest status is so they may transmit the virus. The No Treatments: leaves of plants infected with this virus derived from its The direct feeding by beet leafhopper are dwarfed, crinkled, and rolled upward causes relatively minor plant damage and inward; veins are roughened and transmission of “beet but its pest status is derived from its often swollen; roots become distorted, transmission of “beet curly top virus” an often with a proliferation of hair roots. curly top virus” an extremely destructive virus disease of The home garden situation is not one sugar beets, beans, tomatoes, spinach, that would warrant the use of pesticides extremely destructive melons and other crops. The beet to manage this migratory insect and leafhopper is the only known carrier in there is no treatment for the disease. virus disease of sugar

beets, beans,

tomatoes, spinach,

melons and other

crops.”

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