Scale Scale

Disease Information


 Many scale species-includingPulvinaria acericola, Pulvinariainnumerabilis and Melanaspis tenebricosa are pests of maples. Scales are unusual insects in appearance. They are small and immobile, with no visible legs. Scales vary in appearance depending on age, sex and species. Some are flat and appear like scales stuck to a plant, while others appear like white cottony masses.

Symptoms and damage

 They feed on sap by piercing the leaf, stem or branch with their mouthparts and sucking. Their feeding can weaken or kill branches. Heavily infested trees are stunted with small flowers and leaves. Leaves may yellow and drop early. 


 A combination of various natural enemies, including ladybird beetles (ladybugs) and parasitic wasps, usually keeps scales under control. In small trees with light infestations, scale can be scraped off or infested branches can be removed and destroyed. In a large tree, controlling scale chemically is not always practical. The size of the tree, the need for specialized equipment and the cost may prohibit this approach. Adult scales are relatively protected from insecticides by their waxy covering. Their immature forms, called crawlers, are susceptible, however. If it is determined that chemical control is necessary, the recommended chemicals include the following: cyfluthrin, lambda cyhalothrin, bifenthrin, permethrin or carbaryl. Apply materials when crawlers appear and repeat in 10 days. Soft scales can be controlled by soil drenches with dinotefuran or imidacloprid. Drench applications are best made in the spring. Dinotefuran may move into trees more quickly than imidacloprid for faster control.


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