If this is your first time reading this column, please read part one of this short course on plant pests. This week, let's talk about scale and spider mites, two very common indoor pests. You'll need the same "tools" listed in part I.
SCALE
I find scale the hardest pest to recognize on my plants. In fact, I was embarrassed earlier this month when I took my Gasterworthia 'Royal Highness' into a plant propagation class to show a new plantlet forming on a flower scape. The first thing the instructor did was show me the scale covering the flower stems! I hadn't even noticed them since they are very hard to spot!
Researchers have identified over 17,000 different scale species with most of them living on only one species of plant. The most common scale has a hard, waxy cover over their body and are called "armored scales". Once they find a "home", they never move again! Another type of scale has a soft body cover and move around the plant. Indoors, you are most likely to see the armored scales.
Scales are small and very difficult to see on the plant. They are round or oval shaped as adults and come may be gray, white, brown or other colors. They look like tiny bumps on the plant stem or leaves and may not be recognized as even being a problem! Scales seldom move from plant to plant without the help of birds and the wind.
The basic life cycle of a scale involves the female overwintering under the scales. She lays her eggs under the shell. When the young hatch, they crawl out from under the shell (this is the only time an insecticide spray would be effective). The males turn into gnats which find females to mate with. The females secrete the waxy shell and remain permanently in the same spot for the rest of their life span.
Typical symptoms of scale include unusual bumps on the plant stems, trunks and leaves. The scale sucks the sap which results in a yellowing of the leaves and may kill the branches. A sooty fungus frequently grows where the scale is feeding and this is the main "symptom" you may spot. The only treatment I know of is to carefully scrape every scale you spot off with a cotton swab or your fingernail if you aren't squeamish! Be sure to look in all the little crevices a scale could hide in! Scales are common outside but inside the only plants I've found them on are succulents and palms. If you can't get rid of the scale, destroying the plant is your other alternative.
Go To Page: 1 2
