The flies are so small that five can fit on the head of a pin. They’re so numerous that their swarms resemble opaque clouds or miniature blizzards. Laborers, suffering sore throats and sore noses from inhaling the flies, must wear masks when working in the fields. “I don’t know a number large enough to identify the quantities,” says Keith Mayberry, a farm adviser at the University of California Cooperative Extension. “It would be like looking up at the sky and trying to count raindrops.”
Infestations of unwelcome pests are nothing new to California . But growers fear this new fly may be the most devastating insect to hit the state’s multibillion-dollar agricultural industry. Entomologists have dubbed the poinsettia whitefly “superbug” because of its resistance to pesticides, its prolific breeding habits and its voracious appetite. Alfalfa crops, carrots, cabbage, lettuce, squash, tomatoes, cauliflower and broccoli have all been severely damaged. Imperial County’s melon acreage, for instance, has already been reduced from 17,000 to less than 1,000. If the superbug continues to multiply unchecked, experts predict that by spring the county’s agricultural losses could reach a staggering $200 million.
In addition, the flies have caused more than $5 million in damage to citrus and table-grape crops in neighboring Riverside County and have devastated the melon crop in western Arizona. Superbug wreaks its destruction by attaching itself to the underside of leaves where it sucks out the sap, draining the plant of needed sugar. The flies are carried by the wind: a 2.5-mph wind is capable of moving whiteflies more than six miles in just one morning. Then, says Mayberry, the flies “just drop and start feeding when they see anything green.”
Scientists aren’t exactly sure how to classify the poinsettia whitefly. In 1986, entomologists first identified this bug in Florida poinsettia greenhouses, theorizing that it was a strain of the sweet-potato whitefly. Somehow the insects made their way to Texas, where, last November, they devastated cabbage crops. That invasion alarmed scientists because sweet-potato whiteflies weren’t known to have a taste for leafy vegetables. A few days later the flies hit California. “The red flag didn’t go up. We assumed it was probably a strain of fly with natural predators that would be able to control it,” says Miguel Monroy, assistant agricultural commissioner for Imperial County. By mid-August, officials realized the severity of the blight. “It’s a disaster for every family dependent on agriculture,” says California state Assemblyman Rusty Areias.
For now, farmers are trying to control the insect by digging up entire fields of infested crops. They’re also praying for cold weather, which lengthens the reproductive cycle. While scientists have yet to positively trace the insect’s heritage–speculation centers on Iran, Israel, Pakistan or Africa–they are making headway in isolating natural enemies. Tiny, black lady beetles have proven effective in greenhouse experiments. Last week the U.S. Department of Agriculture identified a parasitic wasp that preys on whiteflies. Field tests could begin by the end of the year. While that’s too late to salvage much of this winter’s crops, there may be life in broccoli yet.
Swarms of tiny poinsettia whiteflies–five fit on the head of a pin–are destroying southern California’s crops. In the last decade, the state’s farmers have battled other pests, too, using chemicals and natural predators.
DATE, ERADICATION INSECT COST 1980-82; 1987-90, Mediterranean fruit fly $170 million 1980-90, Other fruit flies $55 million 1982-87, Boll weevils $10 million 1983-85, Japanese beetles $5.6 million 1980-86, Gypsy moths $2 million
