Phenology of the Hemlock Woolly Adelgid (Hemiptera: Adelgidae) in Northern Georgia

Understanding the seasonal phenology of an insect pest in a specific geographic region is essential for optimizing the timing of management actions or research activities. We examined the phenology of hemlock woolly adelgid, Adelges tsugae Annand, near the southern limit of the range of eastern hemlock, Tsuga canadensis (L.) Carriere, in the Appalachians of northern Georgia, where adelgid phenology has not been previously reported. Adelges tsugae-infested hemlock trees were visited at various sites from 2004 - 2007. Two hemlock twigs were collected from each of 3 hemlock trees per site, except during the final 3 months of sampling when 1 twig was collected from each of 3 trees per site. Progrediens adults initiated oviposition by midMay, 2 - 4 weeks earlier than has been reported for more northern parts of the adelgid range. Sistens eggs were present until late-June (2006) or early-July (2004 - 2005). After aestivation, sistens nymphs resumed development by early October. Sistens adults were first found in early January and were present until midMay. Progrediens eggs were noted as early as February (2005 - 2007), were abundant in March and April, and persisted until midMay. Progrediens crawlers were present by early March and occurred throughout the next 2 - 3 months. Progrediens adults were found between midMay and late June. This information may be used to help optimize release of biological control agents to insure proper synchronization with adelgid life stages and to aid in collection of food for predator rearing facilities.