Parking at a local restaurant today, I noticed the blackened trunks of some topped crape myrtles – the tell-tale sign they were infested with crape myrtle bark scale. This relatively new pest to the U.S. has been rapidly spreading across the south. A horticulture friend commented he saw infested crape myrtles at the new mall on the south side of town. I checked them out, and while the trunks were blackened, there was no sign of living scale. These scales are bright white, and when squished, they ooze a bright pink.
At the restaurant, I also noticed the absence of the white scales. But then, I also spotted a cluster of pupal cases of the twice-stabbed lady beetle. This voracious insect has been noted to do a pretty good job of cleaning up a scale infestation, and obviously they had done their job on these trees. An even closer examination showed a couple of the adult lady beetles still hanging around on this chilly day.
I was recently asked about getting the black sooty mold (which grows on the scales’ secretions) off using a brush and a soapy solution, and that will help some. The bark on crape myrtles regularly peels off (called exfoliation) often revealing a very attractive inner bark of contrasting colors. These parking lot crape myrtles were popping off the crusty, ugly bark, and underneath was the typical light, pretty bark we admire so much.
So, while this scale is still bad news, the good news is there seems to be a good supply of these beneficial predatory lady beetles that can keep the scale population at a low level. And the sooty mold is a permanent feature, but it sure mars an otherwise beautiful tree (if they haven’t been topped)!