Euonymus scale

Appearance

Female scales have a pear-shaped, dark brown scale covering. Males are more slender than the females and are white with a yellow cap on one end. The male scale covering has three ridges running its length. Both sexes are easily observable on plants and are normally 1/16 inch long. All stages are yellow when observed beneath the scale covering.

Behavior

This key pest causes injury to host plants by removing fluid from non-vascular plant cells. It does this with its piercing-sucking mouthparts that results in a reduction of plant health and yellowish stippling or spotting of the foliage. Heavy infestations may occur on twigs or leaves that can cause defoliation of the plant. An infestation of this armored scale may result in twig dieback or death of the plant.

Reproduction

This armored scale overwinters as fertilized females. They begin laying eggs beneath their protective cover in late April and May. Eggs hatch over a 2-3 week period into first instar nymphs called crawlers. The crawlers wander over the bark and foliage for a short time, settle, and then begin to feed. Four to six weeks are usually required to complete development to adults. Males feed and develop under their waxy covers, mate with the females, and die. A second generation of crawlers is produced during late July through August. There is continuous overlapping of broods, so that all stages may be found during favorable conditions.

Predators

Lacewing nymphs; Lady beetle - Chilocorus kuwanae