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Pest Information

Black Pineleaf Scale

Black Pineleaf Scale

  • Latin Name: Nuculaspis californica
  • Common Name: Black Pineleaf Scale
  • Latin Family Name: Diaspididae
  • Other Names: N/A

Pest Details

Black Pineleaf Scale
Black Pineleaf Scale
Black Pineleaf Scale

Origin:

Native to North America, and distributed across the entire eastern half of the U.S. and into southern Canada, as well as in all states from the Rocky Mountains to the Pacific Coast. It also has been found in localized areas of mountains in northern Mexico and into British Columbia.

Biology:

This species feeds only on conifers, but attacks a wide variety of species of pines and fir trees. Infestations usually are localized, but now and then massive outbreaks occur that cover thousands of acres of forest. Severe infestations have the potential to seriously weaken or even kill host trees. In northern climates there is one generation each year and in warmer, southern regions there may be two generations. Like other scales the eggs are produced by the female under her protective wax cover, and these hatch in the spring to the mobile crawler stage. The crawlers move about to infest other parts of the tree, or may be blown by strong winds to other nearby trees. After 2 to 3 weeks the crawlers become sessile, feeding at one point and beginning to form the wax shell over themselves. Winged males will be produced in late summer to mate with females, and the adult females overwinter.

Identification:

Found only on conifers, where they attach to the needles. The adult female scale is dark gray in color with a lighter colored peak on top. They are oval in shape but generally flattened and small. Feeding damage often causes a yellowed area on the needle.

Characteristicts Important to Control:

Infestations of only a single scale for each 2 inches of needle are considered insignificant with respect to health of the tree. When scale numbers exceed 20 per 2 inches of needle it can lead to premature loss of needles, shortened and weakened foliage, and ultimately death of the tree. The weakened tree becomes more susceptible to attack by bark beetles, which may be the cause of the death. Several natural phenomena help keep populations acceptably low, including minimal use of insecticides that kill natural predators and parasites and early onset of cold temperatures. Dormant oil applications to foliage and terminal stems help kill the overwintering scales, and applications of contact insecticides timed to the emergence of the exposed crawlers will effectively kill them. Soil or trunk injections of systemic insecticides may also be effective where practical.

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