Elongate Hemlock Scale is a species of scale insects that is armored with a hard, waxy covering. The insect damages hemlock needles by inserting needle-like mouth parts into leaf tissue and removing cell fluids.
Symptoms the host tree experiences include:
- Yellow spots developed on the upper surface of hemlock needles
- small, oblong flattened insects on the lower needles
- yellowing needles and defoliate in severe infestations
- trees appearing off-color with a sparse canopy
The elongate hemlock scale is a pest of various hemlock species, including the native eastern hemlock and California hemlock. This scale is also occasionally found on yew, spruce and fir, although damage is not usually severe.
Management and Treatment
Natural insect predators of the scale exist, but they cannot be solely relied on for effective control on valuable ornamental hemlocks. A winter oil treatment plus one or two applications during the growing season can provide effective control. Adequate scale control may also take a few season if it is a large population.
Soil injection of Davey's slow-release fertilizer Arbor Green PRO® will increase tree tolerance to scale damage and also speed recovery from previous scale feeding damage.