PINE NEEDLE SCALE
The Pine Needle Scale can be found anywhere host its plants grow, but the heaviest infestations occur in the eastern half of the United States. This insect weakens its host by sucking sap from the needles. An infestation of Pine Needle Scale can be throughout a plant or isolated to just a single branch. A prolonged infestation can kill a plant or weaken a plant, thereby making it susceptible to attack by other insects or diseases.
TREES AND SHRUBS ATTACKED BY PINE NEEDLE SCALE
Almost all pine tree or pine shrub species and many species of spruce are susceptible to Pine Needle Scale attack. This scale has also been found on Cedar, Concolor Fir, Douglas-fir, Eastern Red Cedar, and Hemlock.
SIGNS AND SYMPTOMS OF PINE NEEDLE SCALE
Look for small, white flecks on individual needles. A high population of Pine Needle Scale insects may cause dead shoots, grayish-green discolored foliage, reduced plant vigor, or sparse foliage.
LIFECYCLE OF PINE NEEDLE SCALE
Scale eggs overwinter beneath dead, female scale insects. Newly hatched scale insects are mobile and are called crawlers. Hatching usually occurs around mid-May, about the time Lilac shrubs start blooming. The crawlers move to a feeding site on the host plant or can be transported to a new host by animals, birds, or the wind. Scale insects secrete a protective waxy coating as they feed and mature around early July. A second generation of crawlers is produced around mid-July.
HOW TO CONTROL PINE NEEDLE SCALE
Trees and shrubs susceptible to Pine Needle Scale should be inspected in the early spring – preferably before Lilac shrubs bloom. Infestations often start on the lower third of a plant. If there is only a small population of scale insects present, and predator insects such as ladybugs or lacewings are present, and insecticide treatment may not be necessary.
Cultural Control of Pine Needle Scale
If only a few scale insects are present they can be rubbed off a needle by hand. When only a branch or two is infested pruning may remove the majority of the scale population on a plant. If a tree or shrub is severely infested then removing the entire tree will prevent the scale insects from spreading to healthy trees.
Insecticide Control of Pine Needle Scale
A dormant oil treatment can be applied in the early spring or fall to achieve some control of overwintering scale insects. A lower rate of dormant oil can also be applied during the growing season to control scale crawlers. Several traditional insecticides are labeled for control of scale insects.
Timing is the most important factor when trying to control Pine Needle Scale insects. The first treatment should be applied when Lilac shrubs are in full bloom – usually late May. A second treatment in late July or early August will target the second generation.
Biological Control of Pine Needle Scale
Several predator species feed on scale crawler, with ladybugs, the twice-stabbed lady beetle, and lacewings being the most notable. It has been observed that a reduction of predator insects, and a corresponding increase in scale populations, may be noticed in areas where municipal mosquito control programs are implemented.