Pest

Hemlock woolly adelgid

Adelges tsugae

A tiny aphid relative that drains stored carbohydrates from hemlock twigs and hides under a white, woolly wax. Heavily infested eastern and Carolina hemlocks can die within four years, healthier ones in 10 or more, and it spreads on wind, birds, deer and nursery stock.

Signs

• White, cottony tufts the size of a cotton swab tip at the base of the needles, under the twigs.
• Easiest to see from late winter through spring, and again from late summer into fall.
• Needles turn gray or yellow and drop, new growth falls off, and limbs die from the bottom up.

What favors it

Eastern and Carolina hemlocks in the East; it spreads on wind, birds, deer and nursery stock.

Prevention

• Check new hemlocks under the twigs for white tufts before planting.
• Keep bird feeders out of hemlocks, and water hemlocks in dry spells.
• Do not feed infested hemlocks with nitrogen; it feeds the adelgid more than the tree.

Crops it shows up on

Evergreens & conifers (pine, spruce, juniper).

Often confused with

Sources

• Hemlock Woolly AdelgidUMass Amherst Extension
• Hemlock Woolly Adelgid on TreesUniversity of Maryland Extension

Why →