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Northern Research Station
One Gifford Pinchot Drive
Madison, WI 53726
(608) 231-9318
(608) 231-9544 TTY/TDD

Hemlock Woolly Adelgid

Biological Control

[photo:] Shows large scale rearing operation of HWA predatorsA concerted effort to identify and evaluate a complex of non-native natural enemies as potential biological controls of the hemlock woolly adelgid (HWA) has been ongoing since the mid-1990s. To date, three imported natural enemies have been released in the eastern United States. Sasajiscymnus tsugae, a lady beetle from Japan, has been released in high numbers across the eastern United States since 1999 and in Connecticut as early as 1995. Laricobius nigrinus, a derodontid beetle from western North America,was first released in five states in 2003 and continues to be reared and released throughout the introduced range of the adelgid.  Release of a third predator Scymnus sinuanodulus, a lady beetle from China, began in 2004 at multiple release sites throughout the infested region.  Foreign exploration efforts to identify other potential natural enemies are underway and have generated some promising new leads including new biological control candidates from Japan and China that are currently in quarantine for further study. Research is focusing on tracking the establishment and impact of already released species and on evaluating the potential of new biological control candidates.

Selected Research Studies

Last Modified: 05/08/2015