A new scale (Information provided by LSU AgCenter Faculty Ricky Kilpatrick, Allen Owings, Dale Pollet and Dennis Ring) has been observed infesting crape myrtles in north Louisiana and Texas cities. This scale is thought to be introduced, and the name of the scale is not yet known.
The scale is a bark or felt scale belonging in the genus Eriococcus. The azalea bark scale is a closely related species, but it has not been observed infesting crape myrtles. The new scale insect may be Eriococcus lagerostroemia, which feeds on Lagerostroemia indica in Japan and China.
The scale excretes honeydew that coats leaves and limbs, resulting in a sticky coating from the excess sugars excreted from the insects’ feeding. Sooty mold grows on the honeydew. This results in a black (sooty mold) coating that appears on the bark of the branches and trunks of crape myrtles. Additionally, white cases are visible, and they enclose the adult female scales.
The insects appear as white, waxy encrustations likely to occur anywhere on the plant but often near pruning wounds or in branch crotches. Up close, the azalea bark scale insect is white to gray in color. Larger female scales "bleed" a pink liquid when crushed. The crape myrtle scale appears pink in color inside the case. Careful examination may reveal dozens of pink eggs under some of the larger white scale covers.
Additional work on management of this insect is needed.
The crape myrtle bark scale has been found in North Texas – in the Dallas area – and in north Louisiana – in the Shreveport area. If you find this scale, please take a sample to the county agricultural agent.
Note: Invasive species sneak into the United States in many ways. Then they spread initially undetected through agricultural crops because plants are not carefully checked before purchase or watched after planting until infestations expand and result in unsightly plantings in the landscape or field. All plants should be carefully examined before purchase and after planting to reduce the potential for invasive species becoming established in our nurseries, cities and yards. When unusual insects or injuries occur, notify your local agricultural agent immediately.
This information is made available by Ricky Kilpatrick, area agent in forestry. If you are unable to download the attached file, please contact the Bossier Parish Extension office at 318-965-2326.
To view the PDF, click here.