Scale insects, particularly those of the armored variety, are basically the bane of landscape managers’ existence. They are one of the toughest pests to control. Cryptomeria scale, Aspidiotus cryptomeriae, is one of these armored scales which is also incredibly hard to detect, because it is covered in a translucent, waxy coating. It can resemble the elongate hemlock scale, but is distinguished by the caramel coloring of the glaucous, brown coating. Numerous conifer species are susceptible to Cryptomeria scale, however, they are most often found on landscape hemlocks and pines and can be a particular nuisance on fir trees when cultivated on tree farms; damage can be very intense for true firs.
Cryptomeria scale will cause chlorotic banding and spotting on needles.
This is the view from the underside of needles on a Fraser fir tree affected by Cryptomeria scale.
Cryptomeria scale appear somewhat similar to fried eggs, they are flattened and coated with a waxy, brownish wax. Crawlers emerge yellow and round to oblong.
Cryptomeria scale can spread quickly and overwhelm stands of trees growing closely together, as planted in nurseries or tree farms. Christmas tree farms growing Fraser, Canaan and balsam firs are especially at risk for growth and spread of this difficult to control armored scale, tree farm owners and managers need to be especially vigilant in monitoring and inspection of their stock. When assessing trees for possible affliction carefully inspect underneath needles on mid and lower branches; scale insects may have a flattened, “fried-egg” like appearance. The waxy coating on immature scale insects is more translucent and becomes darker as insects age. When populations are dense, symptoms become visible on the top of the needles appearing as chlorotic bands and mottling, due to the scale insects feeding on the chlorophyll, will be most obvious on lower branches.
Similar to the life cycle of other armored scales, Cryptomeria scale have several generations of crawlers over the course of the growing season. In the northeast and mid-atlantic there are usual 2 generations, one in June and then another in August. Crawlers are lemony yellow and can be distinguished easily due to the contrast. Crawler generations, unfortunately, persist for 4 weeks or more, although the population surge is most often observed in the first 2 weeks.
Several control strategies and methodologies exist for managing Cryptomeria scale populations. Consult with your arborist if you suspect any of your conifer trees has a scale problem, they will help develop a plan suited for your landscape and the level of control necessary.
