|Biological agent type
Plant species attacked
purple loosestrife (Lythrum salicaria)
Click on image to view larger photo.
Images by Eric Coombs, Oregon Department of Agriculture.
If images are downloaded and used from the ODA web site please be sure to credit the photographer.
Site of attack
Roots and foliage.
Mode of attack
Larvae mine the roots and stems, adults feed on the edges of leaves. The weevil may help to dampen the boom/bust cycle caused by the leaf beetles.
Adult and larval-internal.
Collection and release information
At this time this agent is limited in distribution in Oregon. Please contact ODA for release information in your area.
History in Oregon
The root weevil Hylobius transversovittatus was released as eggs in 1992. Adults were reared out and released in Marion and Polk Counties in 1993. Weevils were recovered at both sites in 1994 and 1995. Adults may live two to three years. The larvae can withstand flooding for several months. A cooperative greenhouse rearing project with OSU in 2001 and 2002 produced many releases that were dispersed throughout Oregon. Rearing is more economical because adults are nocturnal and difficult to collect in the wild. The project provided 39 releases for 14 counties. In 2005, a cooperative weevil rearing project was initiated with the Army Corps or Engineers to provide adults for areas along the lower Columbia River, where tides make establishment of the leaf beetles tenuous.
Release status in State
Click on map to view larger image.