scale on branch with antsIt’s very common to see certain varieties of trees and shrubs lose color, fullness, and even life because of scale insects feeding on them. There are hundreds of scale insects that feed on ornamental trees and shrubs in our area. Knowing each one and its specific treatment recommendations isn’t the property owner’s first priority, but knowing how to identify and recognize scale activity and damage on plants can mean the difference in replacing or maintaining costly landscape plantings. Scale is often difficult to notice because of its small size and the fact that it isn’t as mobile as other insects.

Generally, there are two types of scales: Soft, or  Hard (armored) Scales. Soft scale characteristics typically include: (1) generally one generation per growing season; (2) produce honeydew (a sticky substance left as they feed); (3) typically overwinter as immature fertilized females; (4) appear convex in shape or resemble a helmet; (5) highly active crawlers (immature life cycle that is very small before you see that visible adult); and (6) have a protective body shell.

Characteristics of hard scales include (1) at least two or more generations per growing season; (2) do not produce honeydew when feeding; (3) typically overwinter as eggs underneath the body of the dead female; (4) appear circular or rounded in shape; (5) crawlers are less active, compared to soft scale crawlers; and 6) separate protective covering.

We deal with several common scale insects on plants on both residential and commercial landscapes in our area. Here are just some of them and links to pictures and more information on them.

Euonymus scale (most commonly found on Euonymus, Pachysandra, and others)

Fletcher scale (most commonly found on Yews, Arborvitae, and others)

Hemlock scale (most commonly found on Hemlocks)

Magnolia scale (most commonly found on Magnolias)

Tuliptree scale (most commonly found on Tulip Poplars)

Lecanium scale (often found on Maple trees)

Becoming an expert on Scale insects takes lots of training and experience. For the average owner of a landscape, there are 5 main basic concepts you need to know:

  1. Learn How to Identify a Scale Problem: First, you need to know what kind of trees you have on your property. Once you know these species, there are typically very plant-specific scales that you could find on them. Learning a few types of scale insects and how they appear is all you will probably need to know you have a problem.
  2. Know What to Do if You Have a Scale Problem: There is no silver bullet for treating scale. You must know what species of plant, which scale you are treating for, and when to treat for these. If you try to guess and just go to the local home and garden store and spray with a generic spray there are risks. First, you could be completely wasting your money because that spray doesn’t work on that specific insect. Secondly, you could kill beneficial insects, making the scale problem even worse. Finally, if you spray at the wrong time, it could be completely ineffective.
  3. Find a Reputable Tree Care Company to Help You: Just because someone sprays trees doesn’t make them any better at it than you. Search for a company that employs Certified Arborists that can not only identify the pest, but teach you how to control the pest as well as implementing a tree care program that will address the concerns listed above.
  4. Know that Ignoring the Problem Will Kill Your Plants: If nothing is done to reduce Scale populations, they will increase in numbers exponentially. As this happens, plants will suffer not only aesthetically, but they will die as they can’t properly photosynthesize. You may be lucky for a few years, but that luck will eventually run out.
  5. Maintaining Plant Health is Cheaper than Replacing Plants: For a fraction of the cost of removals and replacements, you can budget an annual allowance to spend on treating these potential problems with a tree and shrub care program before they become irreversible diagnoses.

Study these pictures of common Scale insects we find regularly. Know what they look like, and get up close and personal with your trees and shrubs. If you notice a bunch of these, it’s time to call in help from a professional.

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