Whole-tree enclosures: A tool to assess introduced predators of hemlock woolly adelgid, Adelges tsugae
Grant, J. F., J. Rhea, G. J. Wiggins, A. Hakeem, and P. L. Lambdin.  2012.  Biological Control of Hemlock Woolly Adeldgid in the Eastern United States, Pp. 105-110, USDA Forest Service, Forest Health Technology Enterprise Team.

Abstract:
This chapter provides a general overview of evaluative tools to assess introduced natural enemies of hemlock woolly adelgid. Emphasis is on the use of whole-tree canopy enclosures as tools to enhance our biological control activities against this invasive pest.