Identification
At barely .05 inches in size, the HWA is tiny but the damage it causes is not. HWA is easily recognizable by its distinctive white, cottony masses that the females produce on the underside of hemlock twigs. These masses, which contain the adelgid’s eggs, are most visible from winter into spring.
Life Cycle
The life cycle of the HWA is complex. It includes several stages: from egg to nymph and then to adult, completing two generations per year. The most significant population growth occurs during the winter, with eggs laid in the spring.
The pest overwinters as nymphs, which mature in spring and lay eggs that hatch into crawlers. The crawlers begin feeding on the sap of the hemlock, inserting their long mouthparts into the tree’s twigs. This feeding continues throughout their development into adulthood, when they produce a new generation of eggs.
Distribution & Habitat
HWA has made its way to the eastern United States from Asia. It has become a significant threat to Eastern and Carolina hemlock trees. These pests thrive in the shaded, humid environments that hemlocks prefer, allowing them to spread rapidly across the forests and landscapes where these trees are prevalent.
The spread of HWA has also been facilitated by the movement of infested nursery stock and natural carriers including wind, birds and other forest animals.
Damage & Symptoms
The act of HWA feeding on the hemlock trees leads to the weakening of the entire tree. HWA infestation leads to severe damage, including needle loss, branch dieback, and ultimately the death of infested hemlocks. Symptoms of HWA damage include a decline in tree vigor, discoloration of needles and the presence of the pest’s characteristic white, cottony egg sacs. These affected trees are also more vulnerable to other stresses, such as drought or secondary pest infestations. Without intervention, infested trees can die within 4 to 10 years of initial infestation.
Management & Control
Managing and controlling HWA requires an integrated pest management (IPM) approach that includes cultural practices, biological control, and, when necessary, chemical controls.
Cultural Practices: Preventive measures such as maintaining general tree health and avoiding the movement of infested materials.
Biological Controls: Ongoing research using the introduction of predator species that naturally feed on HWA is showing promising results.
Chemical Controls: Focused chemical applications may be necessary in cases of severe infestation.
Prevention
Early detection is key to managing and controlling the spread of this pest. Preventing HWA infestations involves a combination of monitoring, selecting resistant tree varieties, and implementing proper planting and care techniques. Regular inspection of hemlocks for early signs of adelgid infestation is the key to early intervention and control.
Are Your Trees and Shrubs Suffering From Tree Mites?
Call 215.799.2016 or click the button above
to take the first step toward a healthier, more beautiful lawn.
