GMF has had a long and fruitful relationship with Carole Cheah, research entomologist with the Connecticut Agricultural Experiment Station's (CAES) Valley Laboratory in Windsor. Carole’s first independent federal grant was for research on balsam adelgids, a significant insect problem in Maine then. She was advised to contact a forester named Darrell Russ at Great Mountain Forest, who might know where to find a stand of balsam somewhere in Connecticut, the southernmost range of this fir. He did, right next to the current GMF Forestry Office, and Carole came to collect and measure adelgid, a demanding process, every week for the next two years.
These sap-sucking aphids damage and can contribute to the death of firs and hemlocks. The genus that infests Tsuga canadensis, the Eastern hemlock, is known as hemlock woolly adelgid (Adelges tsugae) and is a native of Asia. First found in Virginia in the 1950s, hemlock woolly adelgid (HWA) now threatens garden plantings and forests across much of the eastern United States. Carole’s research has since turned to HWA, and her 2017 publication mathematically modeled 15 years of data from multiple forests, including GMF, to predict HWA mortality in cold weather. Linear regression analysis suggested the absolute minimum daily winter temperature was the most critical factor. The model predicted that 99% mortality of the winter population should be achieved at -17 degrees Fahrenheit in northwestern Connecticut.
On February 4, conditions permitted Carole to test her model: Russell Russ measured minus 17 degrees F. at the GMF weather station. Carole came to collect samples and calculate the percentage of woolly adelgid survivors. Carole was pleased to find that the mortality rate exactly matched her prediction.
GMF has been releasing Japanese lady beetles, an HWA predator, to control the spread of these insects. The findings also allowed Carole to recommend that GMF reduce the number of beetles to be released this summer so they don’t go hungry (more to come on this topic, including the complex life cycle of HWA).