A new invasive scale of crape myrtles has recently been detected. Current evidences suggest that the species is Eriococcus lagerostroemia, a native to the plant host to Lagerostroemia sp., also found in China, Japan, Korea, India, Mongolia, South Korea and United Kingdom.
Current hosts in the US:
- Crape myrtles (Lagerstroemia sp.)
Potential hosts (not yet reported in the US):
(Click scientific name for distribution in the US)
- Pomegranate (Punica granatum)
- Axlewood (Anogeissus sp.)
- Japanese/Littleleaf Box (Buxus microphylla)
- Chinese Hackberry (Celtis sinensis)
- Sissoo/Indian Rosewood (Dalbergia sp.)
- Japanese/Kaki/Asian Persimmon (Diospyros kaki)
- Common Fig (Ficus carica)
- Needlebush (Glochidion puberum)
- Soybean (Glycine max)
- Border privet (Ligustrum obtusifolium)
- Mallotus japonicus
- Paradise apple (Malus pumila)
- Myrtle (Myrtus sp.)
- Raspberries, blackberries, dewberries, etc. (Rubus sp.)
Scale insects (order: Hemiptera) are similar to aphids, in that they tend to be relatively immobile for most of their feeding life and excrete honeydew. The honeydew can act as an inoculant for other pathogens, such as sooty mold, causing the blackening of tree bark and leaves. As a result, the crape myrtle can lose its aesthetic touch and decrease in its ability to absorb light into its leaves for photosynthesis. There are different types of scales, such as armored scales (Diaspididae), soft scales (Coccidae), mealybugs (Pseudococcidae) and felt scales (Eriococcidae) (full list of scale families). The crape myrtle bark scale (CMBS) is a felt scale, Eriococcus lagerstroemiae Kuwana (Coccidae), thought to be host-specific mainly to crape myrtle and pomegranate, although we have yet to see any infestations of pomegranate trees in the US. People have reported infestations in East Texas, from Dallas, Tyler, and Longview. Please contact me with any sightings of this pest using the form or contact. We currently do not know the most effective means of managing the pest, although some have reported varying success with insecticidal soaps (applied directed) and neonicotinoids (applied to the soil).
The following recommendations come from an AgriLife Extension publication (03/14: full publication PDF):
- If you have a high infestation, first wash the trunk and reachable limbs of the tree with a brush and mild solution of dishwashing soap. This will help make the pesticide application for effective.
- Systemic insecticides have shown to be the most effective to date; apply clothianidin, dinotefuran (Greenlight Tree and Shrub Insect Control with Safari), imidacloprid (Merit or Bayer Advanced Garden Tree and Shrub Insect Control) or thiomethoxam (Meridian) as a soil injection between May and July. Give several weeks after application of systemics for active ingredient to reach throughout the plant.
- Some lady beetles, such as the twice stabbed lady beetle, are considered effective predators of CMBS, but is often too late in the season to prevent aesthetic damage from sooty mold.
Texas A&M AgriLife Extension | Crape Myrtle Bark Scale: a New Exotic Pest (PDF)
UofA Research & Extension | Crape Myrtle Bark Scale: A New Insect Pest (PDF)