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Scales are small sedentary insects that secrete a hardened shell over them as they feed. Eggs hatch under the shell and the immature "crawler" stage moves to new growth of the host plant. They suck plant sap and large numbers can harm trees. Mealybugs resemble scale insects but they do not secrete shells, are larger, and more mobile. Mealybugs often are covered with waxy secretions and they seem to live in congregations.

  Oyster shell scale

Oyster shell scales have a characteristic shape and are very common on ash trees as well as others. They sometimes are so numerous that they look like the bark of the tree.

  Pine needle scale

Pine needle scales are white and about 3mm long. The older scales are very easy to see on the host needles. High populations can cause stunted needle growth and and sparse looking plants.

  Soft brown scale

Soft brown lecanium scales occur on many hosts. These large brown hemispherical insects are easy to spot. Although easy to see, most of the time they are not numerous enough to cause serious damage.

  Spruce bud scale

Spruce bud scales occur at the base of small branches and are about 1/8 inch across causing them to be mistaken for twig or needle buds. They are reddish brown and usually in clusters. They can produce large amount of honeydew.

  San Jose Scale

San Jose scales can infest almost any tree in Idaho. They can be distinguished by their characteristic volcano-like shape with a raised center surrounded by a black ring. It can have up to six generations per year and cause serious damage if left unchecked.

  Cottony maple scale

Cottony maple scales are fairly common in Idaho. It is easily recognized by its large size and cottony masses. The scale is under a flat brown cap and the waxy secretions come from under this cap. It attacks several species of trees.

   Mealybug

Bodies covered with wax or filamentous waxy secretions are characteristic of mealybugs. They feed on all parts of the plant, including roots, and reproduce all summer. Many times they are controlled by natural enemies.