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For Immediate Release: May 21, 1999 Contact:

Hope Gruzlovic

When 78,000 Japanese ladybugs left the shelter of NJDA’s beneficial insect laboratory in Ewing last year to wage war against the hemlock woolly adelgids destroying the state’s native hemlocks, the big question was how they’d manage over the New Jersey winter.

But the news is great! Surveys conducted this month confirm that the imported beetle did overwinter in the Garden State and has now established colonies in several locations. Additional releases have already been made this year in the state’s hemlock stands to bolster the predator’s numbers against the pest.

The imported ladybug eats only adelgids and will not compete with native ladybugs. Only time will tell whether the Japanese ladybugs will be able to control the adelgid infestation and save the remaining hemlock forests.

Hemlock woolly adelgid, a destructive insect, is native to Japan and China but was accidentally introduced into the eastern United States a few decades ago and has spread throughout the northeast. The female adelgid lays her eggs in a woolly mass near the tips of the branches. The adults and nymphs feed on the sap of the tree, removing nutrients and causing the tree to weaken and die.

The adelgid causes so much damage because it has no natural enemies here to help keep it under control. Although a number of natural and synthetic chemicals are available to control this pest in nurseries and in domestic landscapes, it is virtually impossible to use them in natural hemlock stands. The natural stands are difficult to reach on foot and the infected trees live beneath dense evergreen canopies that can’t be penetrated by aerial chemical applications. NJDA’s beneficial insect laboratory began producing the ladybugs in 1997 from stock collected in Japan by the Connecticut Agricultural Experiment Station. This insect production initiative was conducted in cooperation with the USDA Forest Service (USDA/FS), the New Jersey Bureau of Forestry and the Connecticut Agricultural Experiment Station. Under a cooperative agreement with the USDA/FS, this year NJDA will also supply a number of other northeastern states with laboratory-raised beetles for releases in infested hemlock stands in those states. Research continues in an effort to find additional beneficial insects that prey on hemlock woolly adelgids.