OLYMPIA --In a continual effort to address rampant Scotch broom infestations, Thurston County has received several thousand seed-eating beetles called Bruchidius villosus. The tiny beetle species larva devours developing Scotch boom seeds. The beetle was released in small shipments in 1999 and 2000, however this year thousands of beetles have been released throughout Thurston County. Repeated introductions of biological control agents for Scotch broom control have been made in Thurston County since 1988. The seed beetle is the newest in the group of insects released to combat broom. Other insects released were a stem boring moth and a seed-eating weevil.
According to Research from North Carolina, up to 85% of broom seeds were destroyed at two sites that were monitored. This year's Bruchidius villosus, were collected from North Carolina.
Scotch broom continues to infest additional areas of Thurston County each year. Seeds adhere to equipment tracks and vehicle tires virtually planting broom in areas that were not infested.
In time, (most likely decades), the germination time period of seeds deposited throughout Thurston County will decrease and broom populations should decline, with the help of the weevil and beetle predation on the broom seeds.
All agents released are approved for release by USDA and have gone through extensive tests to ensure beneficial plants are not affected.