In the war against the exotic insect, the hemlock woolly adelgid, a biological breakthrough is occurring. At the New Jersey Department of Agriculture's Phillip Alampi Beneficial Insect Laboratory in Trenton, New Jersey, scientists are rearing mass quantities of a tiny Japanese ladybug that has a huge appetite for the tree-killing hemlock woolly adelgid. The predacious ladybug-a type of beetle-is named Psedoscymnus tsugae. It is small as a poppy seed. Natural resource managers will use it as a biological control method to save environmentally precious hemlock trees.

Bob Chianese, chief of the Bureau of Biological Pest Control for the New Jersey Department of Agriculture said, "I'm very excited about P. tsugae. For 10 years I've watched the hemlock wooly adelgid spread and kill a lot of the hemlock forests in New Jersey. A biological cure was the only realistic hope to save the trees, and P. tsugae may help us reach this objective."

Eastern and Carolina hemlocks (Tsuga canadensis and T. caroliniana, respectively) ranging from North Carolina to Massachusetts have been attacked by the adelgid, which kills the trees by sucking out nutrients. Individual hemlock trees can be treated in parks and yards, but until now there has been no hope of controlling the adelgid in forest settings. Hemlock stands are among the only old growth forests in the East, and are of great importance to wildlife and water quality. In some places, no other species can fill hemlock's environmental niche.

Credit for the discovery and most of the research behind P. tsugae belongs to Dr. Mark McClure, a scientist at the Connecticut Agriculture Experimental Station. He found the beetle in 1990 during a search for hemlock woolly adelgid predators in Japan, where the pest is native. Dan Palmer, lead research scientist for P. tsugae at the Phillip Alampi Beneficial Insect Laboratory said, "It takes tremendous effort to locate the screen biological control agents. Dr. McClure's finding is extraordinary. The job now is to rear large numbers of P. tsugae to improve its odds of surviving in the field, and to make it affordable and widely available."

Efforts to rear P. tsugae at the laboratory have been successful. Scientists plan to release the tiny predator in New Jersey forests this spring. Because of the environmental importance of hemlock forests, the US Department of Agriculture, Forest Service has provided more than $1 million for research to control the adelgid.

For more information, contact the USDA Forest Service, Northeastern Area, State & Private Forestry at 610-975-4186.

Hemlock Woolly Adelgid

DOB: First discovered in the US in 1924.

Appearance: Aphid-like insect.

Sex: Both.

Height: Approximately 2 mm.

Hair: Cotton-like; white.

Color: White.

Last Seen: Smokey Mountains, and north to the mid Hudson River Valley and southern New England.

Modus Operandi: Feeds by inserting its sylet (piercing and sucking mouth parts) into a young twig, sucking the sap, and retarding the growth of its host tree. The adelgid may also inject a toxic saliva into the tree, that disrupts plant growth hormones and modifies vascular tissue. The adelgid itself is not visible to the naked eye, but the white woolly secretion that protects the adelgid and its eggs is visible and indicates infestation. These white masses are distributed on the newest growth throughout the tree. Tree needles become discolored and change from deep green to grayish green, eventually dropping off prematurely. The loss of new shoots and needles seriously impacts tree health, and death can occur within a few years. The hemlock woolly adelgid is believed to spread at a rate of about 20 miles per year. The mechanism of dispersal is wind, birds and mammals.

Origin: Believed to be Asian

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