Cottony Maple Scale 

Have you ever looked up into one of your trees and it appears that someone has glued popcorn to the branches? Worse yet, have you ever parked your car in the shade and come back to find sticky sap covers it? The same may be true of your lawn furniture, or deck, if they are located under shade trees. The cause of this annoyance is a tiny insect known as Cottony Maple Scale. This insect is active throughout the United States and attacks many shade trees and shrubs, but it is primarily found on soft Maples and Lindens. 

Types of Cottony Maple Scale 

There are many types of scale insects and several of those produce a white cotton-like mass. Scale insects are identified by a hard shell that protects them from predators and the weather. The female passes the winter as a small, brown scale less than 1/8” long. They attach themselves to the bark of small branches and twigs. In the spring, as soon as the sap of the tree starts to flow, the female grows rapidly and begins to deposit her eggs in the cottony mass of wax that she secretes under her protective scale cover. So much wax is secreted that the scale will rise off the branch and the female will be pushed from her protective shell. 

Cottony Maple Scale Characteristics 

The cottony mass resembles popcorn and, if the population is high, the ‘kernels’ will line up along the branches and twigs. The female will deposit 1,500 to 3,000 eggs before she dies. The eggs hatch in June and July. The tree may become weak if the infestation is severe and repeats for several years. The weakened tree is more susceptible to attacks from bark beetles or other boring insects. Mating occurs when the crawlers mature in August or September. The males emerge as small winged individuals that have non-feeding mouthparts. They will mate and die within one or two days. After mating, the females will crawl back to the branches and twigs of the tree where they will spend the winter. They will produce a hard shell to protect themselves during that time. 

Controlling Cottony Maple Scale 

A tree maintenance application of dormant oil in the late winter/early spring will help to control the over-wintering females. 

Damage may result on certain plants when sprayed with dormant oil, so it is important to read and follow all label directions

Several predacious insects feed on different stages of the Cottony Maple Scale. Many wasp and fly parasites are known to feed on the mature females. The Twice-Stabbed Lady Beetle (named for the two striking red spots against a jet black shell) is a major predator of all stages of the Cottony Maple Scale. The female will adjust her egg production to the population of the Cottony Maple Scale. Since the Twice-Stabbed Lady Beetle is so efficient in controlling the scale population, it is usually not necessary to spray for the crawlers. Many tree maintenance products that are used to control the crawlers will, also, control the predators that feed on them. Dormant oil applications are the best defense against future outbreaks of the Cottony Maple Scale. Once again, please read and follow all label directions of any lawn and tree care product that you use

Contact your neighborhood Spring Green professional to receive the proper advice, products, knowledge, and timing to control Cottony Maple Scale or many other landscape problems. 

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