These beneficial wasps eat dozens of species of flies that are known to bite humans and animals. So ranchers and farmers buy wasp-laden fly mummies from Blehm, which they then spread around their barns. Blehm's insectary is just one of eight such facilities in Ventura County, making this part of California the mecca for beneficial bug businesses in the United States. Novartis' most popular product is Persimilis , a predatory mite used by strawberry and ornamental plant growers. This tiny creature can eat as many as seven adult spider mites or 20 eggs per day.
Spider mites feed on the leaves of strawberries and ornamentals.
Persimilis became popular among California strawberry growers in 1987, when Plictran, a pesticide for spider mites, was suddenly withdrawn from the market because it was considered dangerous to human health. And beneficials were the only option. According to Cahn, one of the benefits of such a system is that pests don't develop resistance to chemicals as rapidly. Then if the farmer is forced to spray, the spray is more effective. Other beneficial bug businesspeople in California take a dimmer view of chemical use.