Felt Scales on Oak
Felt scales are a family of scale that include Azalea bark scale, crepe myrtle bark scale, European Elm scale, and Oak Arachnid scale. These scales all have a felted covering that is most apparent when adults are producing eggs. Female oak scales are producing eggs right now. They produce a fluffy felted egg case with at least a hundred or more eggs that will hatch in the coming weeks.
The crawlers which are called first instar nymphs move to new growing branches to feed. They will mature in mid-summer and produce a second generation. Willow oaks and other species can become heavily infested with Oak scale this time of the year through much of the trunk and branches and will be covered with the felted egg casings that look like the head of a cotton swab. These scales also produce honeydew, which will coat the leaves and surfaces below the trees and can foster black sooty mold.
Little is known about the management of these scales. However, as with other scale targeting management efforts toward the crawlers, is best horticultural oil or insecticidal soap applied thoroughly once eggs hatch should help reduce the population. It is important to pay attention to whether the scales are moving or not. There are lady Beetle species that are scale predators and mimic the appearance of felted scale and mealybugs as a larva. These ladybugs or lady beetle larvae will be crawling around the bark on trunks and branches this time of the year and sometimes in great numbers please do not make the mistake for these pests. Lady beetle larvae they do move scales and mealybugs do not.