Seasonality, Distribution, and Biological Control of Crapemyrtle Bark Scale, A New Invasive Threat in Tennessee

Crapemyrtle bark scale, Acanthococcus (= Eriococcus) lagerstroemiae (Kuwana), an invasive pest from Asia, is a threat in the United States. to crape myrtles grown in ornamental nurseries and in landscapes. Although mortality to crape myrtles is rare, its negative effects on aesthetics is considerable. It should affect the sale (valued at >$66 million wholesale) and use of crape myrtle in landscapes. This pest species has been found in numerous states, including Tennessee, where little is known about its state-wide distribution, lifecycle, biology, natural enemies, and impact on crape myrtles. The purpose of this two-year study is to gain additional knowledge to mitigate crapemyrtle bark scale before it becomes an economic barrier for crape myrtle production and growth. This pest was first found in Shelby County in Tennessee in late 2013; as of July 2021, crapemyrtle bark scale had been documented in fifteen counties (nine of these counties are in western TN) in Tennessee. It has now been found in four major metropolitan areas (Chattanooga, Knoxville, Memphis and Nashville,), and moderate to extensive damage is apparent in these areas. Biweekly sampling of crapemyrtle bark scale suggests that the lifecycle of crapemyrtle bark scale in Tennessee encompasses eggs, three nymphal instars, and adult females (sessile) and winged males, with two or three overlapping generations per year. Overwintering populations of third-instar females, adult females, and pre-pupal/pupal males were found in mid-February. Populations of several species of lady beetles were found to reduce crapemyrtle bark scale densities at some locations. This paper will describe the results of this study highlighting distribution, seasonality and lifecycle of crapemyrtle bark scale in Tennessee.