What's eating my eastern hemlock?

Eastern Hemlock is devastated by hemlock woolly adelgid, an invasive pest that has killed millions of trees across the eastern US. Spider mites, elongate hemlock scale, and deer browsing also cause significant damage. Early treatment with systemic insecticides is critical — adelgid-infested trees can die within 4–10 years without intervention.

White woolly egg sacs at needle bases; needles gray-green then drop; progressive branch dieback from the bottom up; tree death within 4–10 years untreated Systemic soil drench or injection of imidacloprid or dinotefuran in spring or fall; horticultural oil on small trees; biocontrol beetle Laricobius nigrinus where available; monitor annually

Armored scales on undersides of needles produce yellow spotting; needles drop prematurely; repeated infestations weaken and kill branches over several years Horticultural oil or systemic insecticide applications targeting spring crawlers; prune heavily infested branches; professional soil injection for large trees

Browse on lower foliage and young leaders, especially in winter; repeated browsing prevents regeneration and strips trees to browse-line height Install deer fencing or tree tubes on young hemlocks; apply deer repellent spray seasonally; plant in areas with lower deer pressure where possible