Gloomy scale, Melanaspis tenebricosa, infests nearly every urban red maple in the Southeast. It devastates trees so we (mostly Adam Dale and Elsa Youngsteadt) spend a lot of time studying why gloomy scale is so abundant on urban trees and how to manage it. The obscure scale, Melanaspis obscura, is common on pin oaks and several other tree species.
Now we have another Melanaspis species to contend with. This one, Melanaspis deklei, infests native wax myrtle, Myrica cerifera. It has been reported from Florida with occasional reports further north. In the last several years my colleague J.C. Chong at Clemson has found increasing number of infestations in the landscapes of coastal communities in South Carolina. Wax myrtle is one of the most common plant species in ornamental landscapes particularly near the coast. M. deklei has not been reported in North Carolina until now. As with many new or rare pests this one was noticed by a landscape professional and Extension Agent in New Hanover County who reported several dead and dying wax myrtles and sent pictures and samples to the NCSU Plant Disease and Insect Clinic.
M. deklei has 3 generations per year in SC. It feeds primarily on stems and branches and causes canopy thinning, branch dieback, and eventually large canopy gaps or plant death. Similar to gloomy scale, crawlers emerge for over a month which makes control difficult. Little else is know about M. deklei biology. No effective management tactics have been identified. Applications of horticultural oil can decrease abundance a little but systemic neonicotinoids have shown no effect. A recent paper on insecticide efficacy appeared in the Journal of Agricultural and Urban Entomology.
Just a week or two ago I reported on crape bark myrtle scale as a new exotic pest that is working its way toward NC. Now we have a new (probably native) pest of another common landscape plant.