Crape Myrtle Bark Scale

Crape Myrtle Bark Scale is a recent (2004) invasive insect from Asia. It started in Texas and has moved into at least 11 other states and initially it is infesting only crape myrtles. In its native area it can infest a number of other plants, but right now it is mostly focused on crape myrtles.

CMBS is a small, white or gray insect (Image 1). It is not a hard or soft scale, it is a bark or felt scale.  The have a waxy coating and exude honeydew like soft scale. They will be found on the stems, large twigs, and trunks, but rarely on foliage (Images 2,3). One of the first signs is the black sooty mold (Image 3 black areas) that is present from the large amounts of honeydew produced by the CMBS.

There may be many generations present at the same time and there can be 2 to 4 generations per year. Males are a winged insect that mates and dies and the female dies after she lays up to 250 eggs.

They hatch in the spring and again in the summer. This stage is the crawler stage and they can stay on the same plant or move by the wind to other plants.

Control


Control can be difficult and require multiple applications to ensure success. If the infestation is severe, it may take multiple applications for multiple years.

First application is during the dormant season and the Hi-Yield® Dormant Spray has been found to be the most effective. Spray all of the trunks and branches very thoroughly and the oil will suffocate the insects. Horticultural oils don’t seem to be as effective at this time.

Next is to spray when the crawlers are out. Your local Extension office or local independent garden center can explain about using double-sided tape to know when to spray. For
this application the Natural Guard® Brand by ferti•lome® Horticultural Oil or the ferti•lome® Broad Spectrum Insecticide are very effective. Spray then repeat at least once 10 to 14 days later.

The easiest application would be to use the ferti•lome® Tree & Shrub Systemic Drench. You only have to do this once per year. Simply mix in a bucket and pour around the base of the plant.

Remember, the shells from the scale will remain on the plant so you may not see that anything has happened; scrape some off on a white sheet of paper and crush them to see if they are dead.
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