All About Scale

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Suzanne Wainwright-Evans

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People are often used to seeing insects hop, crawl and fly around. That’s why when they see a scale insect they don’t recognize it as one.

What does a scale look like, and what type of damage do they do?

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Indian wax scale is a type of soft scale.

Typically, female scales attach themselves to a branch (looking like little bumps) and don’t move for most of their life. They can basically be divided into three groups: armored scales, soft scales and mealybugs (which are covered in another article).

Armored scales make up the largest family of these types of insects, but they’re the smallest in physical size, only measuring 1-3 millimeters. Females are hidden under a scale covering not attached to the insect’s body, but to the plant. This covering is formed by the insect’s ability to secrete a waxy substance in combination with molted skins. Armored scales don’t have mouthparts, they come in a variety of colors and vary in shape from circular to teardrop. Male scales are smaller and more elongated then the female in the immature stage. Some examples are oystershell scale, tea scale, false oleander, cycad aulacaspis scale and white magnolia scale.

Female armored scales keep their eggs under their scale coverings for protection until they hatch. Called “crawlers,” these immature, freshly hatched scales are only about the size of a pinhead. (They get their name from the fact that they crawl to new growth to settle.) Once a location is selected, female crawlers attach themselves to a plant, losing their legs in the first molting. They remain sessile for rest of their lives. The immature males also feed on plants, but then they pupate into mobile adults. Some develop wings (looking similar to flies), while others just crawl.

Facts

If there’s a soft scale population in your garden, ants are usually present. They farm and protect scales from biological controls.

Tips

Treat scale when they’re young and in the crawler stage.

Definitions

Chlorotic: When a plant looses its healthy green color and starts to turn yellow. (This can be due to insects, disease or nutritional problems.)
Crawler: Immature stage of either a mealybug or scale insect.

Faqs

Q: Once I treat the scale problem in my garden, how do I know if the insects are dead?
A: One method is the “squish test,” where you just squish the scale and see if there’s moisture present. This isn’t always foolproof, though. Since scales are covered by a waxy coating, this can help hold in moisture after the insects are dead, so they may still by juicy a month after death.

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All About Mealybugs
Learn how to identify what mealybugs are by understanding their life cycle and the damage they cause, as well as learn how to control these plant pests.
All About Aphids
Aphids those commonly found insects in your garden are easily controlled with simple techniques.

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