Two main monitoring techniques are currently used by crapemyrtle bark scale researchers: double-sided sticky tape and branch counts.
Double-sided sticky tape: Just like it sounds, this technique uses double-sided sticky tape (such as Scotch Double Sided Tape, 3/4-in) wrapped around individual branches to catch the first crapemyrtle bark stage crawlers. By placing tape around 3 or more branches per crapemyrtle and replacing weekly, one can determine the number of crawlers that have emerged and walked over the tape over the span of a week. Although this technique does not count adults, sooty mold, or even older nymphs, it provides an idea of relatively change in crapemyrtle bark scale crawler numbers over the season.
Branch counts: Cut off the terminal 30 cms off a few branches (3-5) per tree and examine under the microscope. In this technique, one can count all life stages of crapemyrtle bark scale: egg sacs, male pupae, crawlers, nymphs, winged males, and even empty sacs. Although this technique provides a greater “picture” of what is going on, the sampling technique is considered “destructive” (because branches are being removed) and samples need to be counted quite shortly after being taken.
The current distribution of crapemyrtle bark scale is provided by eddmaps (eddmaps.org/cmbs/distribution.cfm). If you have found crapemyrtle bark scale in a location that has not been confirmed below, please proceed to eddmaps.org/cmbs/report.cfm in order to create a new sighting.
Time lapse of CMBS spread in the continental USA
Current distribution map of CMBS in continental USA
Annual Population Cycle
The most vulnerable stage of crapemyrtle bark scale to insecticides are the immature nymphs. To determine when the nymphs first come out of the eggs to start feeding, we have been monitoring scale nymph populations on a weekly basis in several locations across Texas and Louisiana.
Our scouting data across all sites and years suggests that first instar crawlers start increasing towards a peak by May 2nd on average. To target crawlers, contact insecticides should be applied starting in April. Monitoring is still ongoing and graphs will be updated as data is collected and consolidated.