How To Identify ‘Armor’ and ‘Oyster Shell’ Scale

scale 300x224 How To Identify ‘Armor’ and ‘Oyster Shell’ ScaleOne particularly common garden pest wreaking havoc on shrubs in the months of May through August is ‘Armor Scale’, also called ‘Oyster Shell Scale,’ or ‘Wax Scale.’


Oyster Shell Scale is a peculiar looking insect, who becomes obvious on your shrubs only after it has begun to create a protective covering over itself. The shell that an active Scale creates can resemble anything from a wad of chewed gum, to a fuzzy ball on the stems and leaves of woody plants.  The white waxy ‘shell’ covering is pliable in early summer months, and emits Honeydew that the insect excretes as it feeds on the sap of a plant. Aged Scale, and dead Scale that have completed their life cycle are dry, hard, and a grey or brown color. They begin to resemble bark before they fall off a plant, but can be pruned out for appearance sake.

Scale are sucking insects, and they and their offspring (called ‘crawlers’) attach themselves to a plant within a few hours of hatching, remaining stationary for the remainder of their life while receiving the nutrients they need from sap.   Female Scale lay eggs inside of their shell, and the ‘crawlers’ emerge in late April or May to wander the plant for a one or two week window in search of a good permanent place for themselves.

While scale in small numbers are not harmful, in large numbers they can kill a plant in several ways.  Large clusters of scale will rob a plant of it’s nutrients, and stop leaf production, killing sections of a plant. Additionally, the sugary Honeydew residue can become a breeding ground for black powdery mold and bacteria, which are deadly to a plant when left unpruned. Heavy Bee and Ant activity around infested plants can be the first indicator of a Scale problem, as the two species are attracted to the Honeydew as an alternate food source.   [Read more...]