Pine Needle Scale

Description

Scale insects are sap-feeding insects that derive their name from the shell-like waxy covering that conceals their bodies.  Pine Needle Scale are considered to be "armored" scales, and appear as white scales, 3 mm in length on needles.  They are elongate and oval.

Life Cycle

Scale insects have a simple life. Eggs are laid under- neath the scale covering of the adult female. When the eggs hatch, tiny immatures, known as nymphs, emerge. Nymphs have legs and antennae and are called “crawlers” because they walk away from the maternal scale to settle at new feeding sites. For most common scales, this is the only stage that crawls about on the plant. When the crawlers arrive at a suitable location, they insert their mouthparts into the plant, and begin to feed on the plant’s sap. The shell or scale character- istic of the species develops soon after feeding begins. The legs and antennae of most species are lost as the nymphs grow. Nymphs and adult females for most species remain at the same location for the rest of their lives. Adult males are tiny, flying, gnat-like insects that fly to new females for mating. Scales may go through one or more generations each year.

Damage

Scale insects feed by sucking say from trees and shrubs through piercing-sucking mouth parts.  Sap feeding by these insects may cause yellowing or wilting of leaves, stunting or unthrifty appearance of the plants.  When heavy infestations occur, it can kill all or part of the plant.  Weakened plants may also become more susceptible to injury caused by drought, severe winters, or other insects.

Management

Scale insects are difficult to control because the waxy  or cottony covering serves as a protective barrier to traditional contact insecticides.  There are some natural controls.  Natural predators such as small parasitic wasps and lady beetles can keep scale populations down.  Adverse weather may also reduce populations.  Mechanical control, such as removing scales by hand or pruning out heavily infested stems, is really only practical on very small trees and shrubs or houseplants.  If natural or mechanical controls are not sufficient to keep the populations down, chemical control can also be used.  Dormant oil prior to bud break , contact insecticide in summer when the crawlers are active, or use of a systemic insecticide are all options for chemical control.