Wasps for Sale : Homeowners Can Go on Offensive in Whitefly Infestation by Buying Batches of the Pest’s Natural Enemy
Tom Bellows has a few thousand wasps he’d like to unload on the public--at $1 apiece, no less.
But these aren’t just any wasps. They are tiny, stingerless predators originally from Israel, with an insatiable taste for ash whiteflies.
Bellows, an entomologist at UC Riverside, heads a unique program designed to help residents fight back against the swarming clouds of whiteflies that have infested the state for the past three years.
The whitefly attacks 100 varieties of trees and shrubs by sucking the vital fluids from their leaves, but most residents know the pest by its habit of swarming in dense, annoying clouds.
The state Department of Food and Agriculture has been releasing the Encarsia wasp, raised at UC Riverside since 1989, and there has been encouraging evidence that the insect is slowly bringing the whitefly infestation under control.
To hasten the spread of the Encarsia statewide, UC Riverside is offering homeowners and city governments the opportunity to seed their own areas. The university is charging only what it costs to raise the tiny predators. But they do not come cheap--$1 a bug, with a minimum order of 250.
“I regret we just can’t give them away. We’re not in the money-making business,” Bellows said. “But that won’t even cover the cost of the program to date.”
The entomologist said he has no idea what the response will be to the wasp sale, but there already have been inquiries from city governments, neighborhood groups and the public.
“We’re prepared to do what we can,” Bellows said.
The Encarsia wasp was introduced to California by Bellows with help from colleagues in Israel, where the wasp and the whitefly are found naturally.
Bellows had begun researching natural predators to the whitefly two years ago, after the pest had spread to virtually every part of California except mountain regions.
The ash whitefly is originally from Europe and North Africa, but is not considered a problem in those areas because natural predators keep its population in check.
When it came to California, it had no natural enemies and soon entrenched itself in gardens and yards from San Diego to Red Bluff.
Bellows looked at several different predators. He finally settled on the Encarsia wasp, which is virtually unnoticeable to humans but deadly to the whitefly.
The Department of Food and Agriculture has been releasing small colonies of the wasp around the state and, given time, those colonies will spread.
But department spokeswoman Veda Federighi said that many homeowners may not like waiting for relief to arrive.
“People are real desperate,” she said. “They’re not willing to wait two years. They want their back yards back now.”
The state has no plans to offer the wasp to the public. But UC Riverside decided it could quicken the spread of Encarsia by taking on sale of the bugs.
“Our research indicates that in most cases, a single release of wasps provides some population reduction at the release site in the first year, and permanent protection in years following with no need for additional releases,” Bellows said.
He cautioned that the Encarsia wasps are of a very specific kind and that other varieties sold in garden shops and nurseries will not work on the whitefly.
Bellows said the wasps are being sold in 250-insect lots, considered the minimum to start a colony.
The university will send the bugs anywhere in the state by overnight mail, but Bellows suggests picking them up in person to prevent handling problems.
All a homeowner has to do is tape the vial of Encarsia to an infested tree and let nature do the rest.
“It’s pretty simple,” he said. “It’s very doable for the homeowner.”
With any luck, residents should begin noticing a reduction in whiteflies by the fall--usually the prime season for the pest.
“You could well see some change this year near the release area,” Bellows said. “My expectation is that next year the population will be vastly less.”
The Encarsia wasps can be ordered by calling (714) 787-3718.
