Without Battle Intelligence, This War Can’t Be Won : Medfly: Aerial spraying of the pest presumes knowledge of its behavior. Problem is, the state’s eradicators haven’t a clue.

In declaring a Medfly “state of emergency” in August, Gov. George Deukmejian gave the State Department of Food and Agriculture and county agriculture commissioners the power to spray malathion at will. Yet the goal of eradicating the pest is doomed, no matter how much of the pesticide is rained on Los Angeles and Orange counties.

The would-be eradicators presume to know the exact locations of Medfly colonies. But they overlook an important behavioral trait of the pest: The fly is territorial. It repeatedly returns to one tree, bypassing the tree with the trap that is only 10 yards away. Thus, it is likely that there are pockets of Medflies throughout the two counties that trapping will completely miss. Worse, when a Medfly is caught, the eradicators don’t really know what that indicates. Are there five or 5,000 others on the loose?

Eradication also presumes that the pest will stay away for many years. Wrong again. Medflies were found in Los Angeles County in eight of the last 10 years, and scientists agree the fly will continue to populate the area because of the enormous volume of travelers moving between California and other countries with Medfly populations.

The State Department of Food and Agriculture, nonetheless, claims its aerial spraying in Santa Clara County in the early ‘80s wiped out the Medfly. Top entomologists have an alternative explanation for the pest’s disappearance: two consecutive cold winters. The adult Medfly cannot tolerate temperatures below 45 degrees or above 105 degrees for more than a few hours. When immature, they cannot survive temperatures below 40 degrees for a similar period of time. The climate in most of California’s valleys and major farming regions is thus not hospitable to the pest.

In any case, aerial spraying is unnecessary, because trees do not need to be drenched with the malathion bait spray to catch a Medfly. The bait is designed to be selectively applied. As such, a short burst of the pesticide from the ground is adequate in residential neighborhoods.

That still leaves the question of whether the Medfly has developed a resistance to malathion. The pesticide kills active adult flies but is largely ineffective during the winter. Beyond that, nobody knows. The effect of malathion on such beneficial insects as bees is less uncertain: It kills them. Similarly, predator insects, such as ladybugs, that are crucial to controlling pests that damage plants or crops are also destroyed by the spraying. By indiscriminately dousing with malathion, the state is preparing the ground for other pests that will require more pesticide spraying.

Humans, of course, also are affected by malathion spraying. The chemical attacks the nervous and immune systems. It may cause cancer or birth defects. But like most pesticides in use today, research on its long-term health effects is incomplete.

Following the aerial spraying of malathion on Northern California in 1981-82, numerous suits were filed against the state. More than $2 billion in damages was sought. Claims to recover the costs of restoring auto paint totaled $16 million, of which $3.7 million was paid. The bill for similar damage to cars in Southern California will likely be much more. The price tag of the health-related suits could be astronomical.

The chemical-intensive strategy of eradicating the Medfly is irrational, wasteful and damaging to our health and the environment. The state would be far wiser to develop a “control program” that would include the release of Medfly parasites and predators, the use sterile flies, occasional fruit stripping, posting of chemical traps or limited applications of malathion bait on trees.