Crape Myrtle Bark Scale

THERE’S A NEW “BUG” AROUND

Is It In Your Garden?

Crapemyrtle Bark Scale (CMBS), is an insect from Asia that attacks crapemyrtles. CMBS, first identified in Texas in 2004, has now spread to at least 12 additional states including Alabama. It has been verified in all areas of both the City of Huntsville and Madison County.

The scale first appears as white or grey waxy crustations around pruning cuts and in the crotches of branches of crape myrtles. If you mash or prick one of these spots it will bleed pink or red. If left untreated it will soon cover most of the trunk and twigs of the tree. CMBS is a sucking insect that “poops” a sticky substance known as honeydew. This substance attracts black mold and quickly becomes unsightly as it shows up as black on the trunks as well as on any foliage or mulch under the tree.

Other common landscape plants that may be susceptible to CMBS are pomegranate, persimmon, common fig, Japanese/little-leaf boxwood, American beautyberry, cleyera, privet, blackberries, raspberries, and possibly azaleas.

The following steps will help in controlling and preventing the spread of this insect:

  1. If buying new plants, be sure to purchase them from a reputable nursery, and before purchase check them carefully for any signs of CMBS.
  2. Always plant crapemyrtles in full sun. Keep them healthy by properly mulching, watering, fertilizing and pruning.
  3. If you suspect that your trees are infected, use a systemic insecticide, such as imidacloprid, when trees begin to show signs of new growth in the spring (late March–May). This insecticide should be applied only once a year as a soil drench; however, it may be necessary to reapply in successive years.  The once-yearly drench may be applied later in the year as long as it is done before the tree begins to lose its leaves. Generic versions of imidacloprid are available.
  4. Be certain you carefully follow the label directions for use of imidacloprid or any other insecticide you use. If you are concerned about the effect of systemic insecticides on foraging insects, remember that when applied correctly these insecticides do not appear to be as harmful.
  5. Biological control is another option.  An Auburn study has had good results with lady beetles on small plants. Several lady beetle varieties have been found to be predators of CMBS, however, the scale multiplies faster than the beetles so beetle lures are a necessary for successful results.

You may refer to the following publication for more information on CMBS including history, possible brand names of insecticides and specifics on their application as well as biological controls such as lady beetles.

Additional sources of information include:

You may receive additional help from the Alabama Cooperative Extension System by contacting the following Madison County Extension Agents:

Marcus Garner: mlg0005@auburn.edu or 256-532-1578

Dr. Rudy Pacumbaba: rop0001@auburn.edu or 256-372-4266

–Master Gardeners of North Alabama