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Catchin’ bugs in the Lari-Leuco container

A better way to monitor predators of the hemlock woolly adelgid

the new containers
The Lari-Leuco containers make it easy to monitor for both predators of the hemlock woolly adelgid. Photo by Bud Mayfield, USDA Forest Service.

New containers make it easier to monitor Laricobius beetles and Leucopis silver flies, two important predators of hemlock woolly adelgids. USDA Forest Service managers and partners have released these predators throughout the range of eastern hemlock to help control the invasive adelgids. After two years, the sites are monitored to see if the predators have become established.

With the new Lari-Leuco containers, both predators can be detected at the same time on clipped branch samples.

To use the Lari-Leuco containers, a bouquet of infested hemlock branches is placed in a central jar. A bottom jar of the container captures Laricobius beetle larvae dropping off the branches. A top jar catches Leucopis silver flies as they fly from the branches.

The container can be constructed by hand using very basic components that cost less than $10 per unit. USDA Forest Service scientists and their partners at Cornell University optimized the container for capturing Leucopis flies by adding an inverted funnel to a preliminary design.

Laricobius larvae can be detected by clipping foliage samples in the early spring, whereas Laricobius adults can be collected by using a beat sheet, which involves tapping a hemlock branch with a piece of PVC pipe or a walking stick to knock the beetles off the branch and onto a white fabric where they can be counted.

Laricobius beetles and Leucopis silver flies are key to the integrated pest management program for hemlock woolly adelgids, along with conservative, strategic use of insecticides and other tactics.

Read the article in the Journal of Economic Entomology. For more information, email Bud Mayfield at