Hemlock Woolly Adelgid and Elongate Hemlock Scale Surveys in Connecticut and Massachusetts 1997-2011

In the eastern USA, eastern hemlock (Tsuga canadensis) is the host plant for two invasive insect species - hemlock woolly adelgid (Adelges tsugae) and elongate hemlock scale (Fiorinia externa). We observed the density of adult hemlock woolly adelgid and elongate hemlock scale on eastern hemlock branches on five occasions over 14 years at 142 stands across a latitudinal transect encompassing 7,500 km2 in Connecticut and Massachusetts to assess whether there is a difference in the response to abiotic conditions (winter temperature, summer temperature, summer precipitation) between the two species, and whether the distribution and abundance of each insect species is dependent on biotic interactions with the co-occurring insect species.