Pesky Household Scales - These Plant Insects Will Suck the Life from Your Plants

Up until a couple of years ago, I had never heard of household scale insects. I've had houseplants ever since my college days back in the 1970s, and in recent years started collecting and growing orchids. I've always had only great luck in growing plants. One of my philodendrons was over 20 years old! You could say my "green thumb" was made of emeralds.

A couple of winters ago, I noticed my houseplants getting sickly. A couple of them died, even though they had adequate light and water. Then I noticed that the leaves of my orchids were covered with slimy brown spots, and the unaffected leaves were sticky. I took one of the leaves to the nursery where I was informed that my plants were infested with scales!

That first winter was a tough one. Even though I bought many different kinds of insecticides, I lost almost all of my orchids. My areca palms were goners - felled by tiny parasites. I am reminded of this because yesterday I took a look at my bay laurel plants, now sitting outside, and they too have scales!

Household scales are extremely tough to get rid of. Once you have a plant with scale insects, the likelihood of them traveling to other plants is extremely high. The scales (coccidae) that were on my plants are soft, light to dark brown and oval, and about 1/8' to 1/4" long. They're so small, it's very easy to disregard them when watering or fertilizing. I suppose they move, but I've never seen it happen - they don't have legs! They resemble spots of dirty water or oil, and when you touch them, disintegrate into a gooey mess. Scales often leave a sticky residue on leaves and flowers. They survive by sucking the sap out of plants, and they reproduce quickly. Your houseplants will then die from the shock of being host to so many insect parasites.

There are some things you must do if you want to curb scale infestation. First of all, isolate the affected plants from other plants. If you don't, sooner or later, all of your houseplants will have scales. In order to eliminate scale plants, you need a good insecticide. The one I highly recommend is Garden Safe Houseplant and Garden Insect Spray. For some reason, this product works best for me. Spray the plant thoroughly, from top to bottom and the bottoms of leaves as well. Take a damp paper towel and coat all of the leaves with the insecticide. While you do this, the scales will be squashed off on the toweling. This can be quite gross, but it's necessary to get the insecticide on all areas of the plant. Don't worry about squashing the insects because this is a good thing. Once you've given the plant a once-over, spray with the product again.

I find it necessary to repeat the treatment at least twice a week. Baby scales are small and easy to miss. It could be too late if you wait until the insects are the size you can see them. Once you have experienced a scale infestation, it may take a long time to fully rid your plants of the insects. If you must discard your plants, resist the urge to reuse the potting soil. Scale insects will also reside in the soil, where it's impossible to see them.

There are some good web sites available that address the scale problem. Iowa State University's Department of Entomology has an excellent site. (http://www.ipm.iastate.edu/ipm/iiin/housepla.html)