From a distance, a white powdery scale infestation on your tree bark may look like a harmless lichen or tree fungus. Upon closer examination, you may see the nymph stage (crawlers) in the white egg masses noted in the picture of an infected Kwanzan Cherry Tree.
Left untreated, these insects feed on the tree and can leave open wounds in the bark where lethal fungus can enter. The most common time to find the crawlers is from June 1st to September 1st. Crawlers can be spread from tree to tree by wind or animals making control difficult. According to the UCONN Cooperative Extension Center scale can “be monitored by using black electricians tape around a three inch portion of the trunk or branch. A thin coating of petroleum jelly spread over the center two inches of the taped area.” When the crawlers become active, they will get tangled in the jelly. This is the ideal time to spray the entire tree with conventional or organic insecticide. Oils and insecticidal soaps are effective in the nymph stage. A second spray may be needed in 7 to 10 days as the crawlers don’t all become active at the same time.