There are two main types of scale insects: armored and unarmored. While both types are protected with wax built up by the insects themselves, the armored species has wax that covers their entire body. Unarmored scale insects on the other hand only have a small shell that covers their back, resembling a turtle shell.

Although the two types of scale insects are small and would seem to cause only minor damage, they both contain large pointy, needle-like mouth parts that are up to eight times the length of their body. These scale insects then insert these mouth parts into tree leaves and limbs, feeding on the tree sap, and when untreated, the continued feeding directly hampers the growth of the tree.

Scale insects can also produce a sticky sap, called “honeydew,” that can create a great environment for fungus to grow and adds further damage to trees and shrubs. Scale insects also kill twigs, branches, resulting in severe damage to an otherwise healthy tree.

Scale insects are mostly dormant over winter, with the unfertilized females begin laying eggs in the spring. These eggs hatch as small legged scale insects who then migrate to a good place to feed, losing their legs soon after while developing their waxy shell. The male scale insects, over time, develop wings that they use to travel from area to area in finding females to fertilize.

In our areas of service, the best time to control scale insects is during the insect’s dormant period with the use of a dormant spray, or when they are crawlers usually in early to mid-summer and looking to reproduce. The most effective application is generally a dormant spray between November and March, preferably February and March. During the mobile crawler stage in early summer, June and July, scale insects can be susceptible to insect-controlling products. Some scale insects can also be controlled with systemic products, but results are not easy to determine.

Do you have a tree pest problem? Talk to a Senske arborist about our holistic tree service.

Soft scale insects are similar to their counterparts, the armored scale insects, except that the waxy shell that is created covers only their back instead of the their whole body. The shell of the soft scale insects are likened to resemble a very small turtle shell. However, like all scale insects, don’t let their small stature fool you into thinking that they are not destructive, because soft scale insects can still cause major damage to your trees and shrubs.

Soft scale insects attach themselves to tree leaves and branches through large mouth parts, at times up to eight times bigger than their bodies, and feed on the nutrients that trees needs to grow. The results can cause tree growth to be hampered. Also, soft scale insects can produce “honeydew”, a sticky substance on the bottom of tree leaves that is an ideal place for tree fungus, such as black mold, to grow.

Common types of soft scale insects include:

Lecanium Scale

• Brown and turtle-shaped in appearance.
• One generation per year.
• Spends winter on twigs and branches.
• Produce large amounts of honey dew that attracts wasps and ants.

Fletcher Scale

• Dark brown in color with a shiny appearance
• Mostly affect arborvitae and yew trees
• Also is a producer of honeydew
• One generation per year

Cottony Maple Scale

• Produces large white egg sacks on tree twigs
• Feeds on leaves in the spring and migrates to twigs in the fall
• Produces honeydew
• Most common on silver maples, but also can affect box elder, apple, beech, cherry and many other trees
• One generation per year

Soft scale insects are best treated in the spring with a dormant spray.

Do you have a tree pest problem? Let Senske arborists help you get rid of scale insects as part of our complete tree service program.

Armored scale insects are small bugs that attach themselves to leaves and branches of trees. While armored scale insects are attached, they insert their large needle-like mouth parts, sometimes as long as eight times the length of their body, and feed on the tree sap. Similar to aphids, during feeding is when these insects cause the most damage to the growth of the trees and shrubs. They also secrete a sticky material called “honeydew”, resulting in additional harm to the tree through the growth of fungus.

Armored scale insects control is best achieved by the application of dormant sprays and pesticides while they are in their mobile state. During this mobile state they are called crawlers, coming out from underneath their protective coating, usually in early to mid summer. Armored scale insects can also be controlled naturally by predatory insects such as lady bugs.

San Jose Scale

• Circular and smoky black.
• Small in size around 1 or 2 mm in diameter, can sometimes be confused for dirt on a plant or bark
• Most widely distributed and destructive to fruit trees, shade trees, and ornamental bushes
• Affect up to 60 species of plants and trees
• Highly reproductive with up to 3 generations per year
• Dormant Spray is the best control

Oyster Shell Scale

• Chestnut brown colored
• Shell is shaped like an oyster
• Eggs hatch in late May
• Mostly effect apple, lilac, dogwood, birch, and elm trees
• Dormant spray is best control

Pine Needle Scale

• Are a pure white color
• Effect ornamental plants and spruces
• Best treated in spring when lilacs are in bloom
• Best controlled with dormant spray or treatment in early summer before crawlers are covered under the waxy protective coating

Euonymus Scale

• The females are pear shaped and a blackish brown color
• Males are elongated and white
• Mostly effect evergreen trees in nursery settings
• Can cause defoliation and branch die back
• Have two generations per year

Juniper Scale

• Females are round with a dirty while color and yellow center (slightly resembling a fried egg)
• Males also are white without the yellow center
• Effect junipers, arborvitae, Cyprus, and incense cedar trees
• Best control is dormant spray or mid-summer treatment

Hemlock Scale

• Are a brownish color
• Are found on the underside of needs of hemlock trees as well as other conifers