Scale Insects - Easily Spotted
Difficult to Eliminate
Scale insects are very slow moving. They are large enough to be readily visible.
They have a relatively long life cycle. They would appear to be easy to control but they still are a very nasty pest on our houseplants.
Why? The large adults are readily visible but by the time they reach that stage they have already been slowly crawling around and feeding on our plants. The adults are a hard shelled scale, just as the name implies and that shell makes them almost impervious to any spray that we might use.
Where Are They? They are most often detected by the mess on the floor or leaves. They secrete a gooey honeydew substance (picture left,) that you may find sticking to floors and furniture and that should cause you to look to the plant directly above. On the plant the sticky substance may be quite black because there is a particular fungus that likes to grow in that nutrient rich goo. Although theses adult scales are quite visible, (top picture,) knowing what to look for is the hard part. There is no visible insect just this hard brown, (usually,) bump on the plants leaves or stems. Flipping one over with the point of a knife will reveal the living insect inside or even the mass of tiny newborns (picture right,) waiting to head out on their own path of destruction.
How Do I Eliminate Them? Physical removal is the best form of defence. By the time you discover scale insects, there may be many of them and they may not all be out in the open. They will lodge themselves in cracks and crevices in a plant and any other cute hiding spot. The standard technique is a cotton swab (actually several by the time you have finished,) dipped in rubbing alcohol. You physically remove them with the swab and the alcohol will dry out any of the tiny transparent crawlers that may be hanging around on that branch. This becomes a rather time consuming process with a large infestation on a big plant and you will have to decide just how much effort that particular plant is worth.
What Plants Host Them? The picture at the top is some newly discovered scale insects on a Date Palm that is one of my
part time houseplants.
Going outside for the summer is where it probably managed to acquire these beasties. Now it is an ugly, unfriendly plant (pictured right,) and my wife suggested just putting it outside in the middle of winter as a cure-all. She knows that is not going to happen because that plant was grown from the pit of a date that my daughter ate and planted when she was about 8 years old.
I will sit with the alcohol and swabs and a bad TV show and spend an hour or so chasing scale. The tricky part is to swab even where there does not appear to be any insects. The young crawlers are usually transparent and very difficult to see, so wipe the branch anyway in an attempt to remove or kill them. The tiny beige specks in the top picture are the immature crawlers.
I’m sure that in the great ecosystem of life there is some predator whose life is dependent upon a supply of scales but he doesn’t live in my house.
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