California ag department unleashes stingerless wasps to fight apple moth

A stingerless wasp no bigger than a grain of rice is the California Department of Food and Agriculture's latest pest management tool in the ongoing effort to control infestations of the light-brown apple moth, an invasive agricultural and environmental pest.

"These tiny wasps are harmless to people and pets, but they have a big appetite for the eggs of light-brown apple moths," said California Agriculture Secretary Karen Ross. "These kinds of pest control measures are the result of CDFA's continuing commitment to the principles of integrated pest management. It's a thoughtful approach that selects management options to achieve results while minimizing detrimental impacts."

The pale-yellow wasps, known to scientists as Trichogramma platneri and Trichogramma pretiosum, are native to California. CDFA plans to augment the wasp populations in areas where moth infestations have recently been detected.

Crews will place small cards with the wasp pupae on outdoor plants in the infested neighborhoods. When the adults Trichogramma emerge, they will seek out moth egg masses in the area and lay their own eggs inside the moth eggs, eventually killing the developing moth when the wasp larvae emerge.

The initial sites chosen for this project are small infested areas in San Luis Obispo and Sacramento counties. Placement of the wasp pupae is scheduled to begin this month. Public meetings were held locally to inform residents of the plans, and residents will be contacted individually by crews as the wasp cards are placed.

"CDFA has a long history of employing biological controls such as these tiny wasps," Ross said. "We've been using them for many years to help protect California's grapevines from the glassy-winged sharpshooter, for example."

The moth is native to Australia and is known to damage crops as well as trees and plants found in urban landscapes, parks and the natural environment. California is the only known infested area in the continental U.S.