Winter Activity for Crapemyrtle Bark Scale, an Urban Landscape Pest

Abstract

Scale insects are some of the most abundant and damaging pests of urban forests in North America. Despite their prevalence, scale insect emergence during the winter dormant season, which could contribute to their population growth and spread and thereby inform management, has not been thoroughly investigated. Crapemyrtle bark scale (CMBS), Acanthococcus lagerstroemiae (Kuwana) (Hemiptera: Eriococcidae), is a nonnative pest of a widely grown landscape tree, crapemyrtle (Lagerstroemia spp.). Now present throughout the Southeast and Mid-Atlantic regions of the United States, CMBS has spread rapidly since its initial detection in Plano, TX, USA, in 2004. The contributions of year-round activity to the insect’s widespread abundance and economic importance are unclear. Here, after infesting crapemyrtles with known numbers of CMBS in Summer 2021, we recorded the presence or absence of CMBS immatures on infested trees from Autumn 2021 to late Winter 2022. We found that active nymphs occurred throughout the entirety of these colder seasons. Additionally, average CMBS density drastically increased from October to March, growing from 28 ± 10 SE insects per plant to 554 ± 133 SE, respectively. Our results highlight previously unknown aspects of year-round crawler emergence by CMBS, which could provide opportunities for landscape managers to use targeted winter applications of less harmful pesticides such as horticultural oils.