Bugged by Cottony Tufts? No Weighty Issues Involved in Getting Rid of Scale
Keep on the lookout for little, white, cottony tufts on houseplants. These tufts, which might appear on plants as unalike as gardenias and jade, are not some mutant flower. These white creatures are members of a group of insects called scale.
The armored scale, don’t have that downy look and stay in place beneath a waxy shield.
The other type, the ones with white, cottony tufts, are so-called naked scale and are represented by mealybugs and cottony cushion scale. The “cotton” is composed of wax filaments.
All scale insects eat by inserting their hollow, pointed stylets into plants and sucking out juice. Plants infested with scale are weakened, often to the point of death.
As the insects feed, they excrete a sweet, sticky liquid called honeydew. On the plant, the honeydew becomes food for a fungus that grows as a sooty coating on the plant. The fungus does no direct harm to the plant but looks ugly and can become severe enough to shade the plant from light.
Cottony cushion scale and mealybugs obviously must be terminated. They are generally easy to keep in line but hard to permanently eradicate.
Poisoning with insecticides is one recourse. Another--often justifiable to prevent spread of scale--is to throw out an infested plant. At the very least, infested plants should be isolated.
There are less aggressive controls. A sure but tedious method for killing scale insects is to rub them with a cotton swab dipped in rubbing alcohol. This is 100% effective as long as you are diligent.
Hot water is another way to kill mealybugs and cottony cushion scale. Immerse the leaves and stems of a plant in water at 140 to 150 degrees Fahrenheit for five to 10 minutes. This treatment should leave the plant unharmed, but to make sure, test a single leaf first.
You can evict mealybugs and cottony cushion scale with a stream of water. They are just barely mobile, so it is unlikely they would clamber back up the stems once dislodged. A dousing with soapy water is even more effective in penetrating the waxy covering.
Mild insecticides such as insecticidal soap and horticultural oil kill scale insects. But these sprays can also damage plants, so before you spray the whole plant, squirt a single leaf or branch and see if any damage appears in a few days.
For added safety, leave the soap spray on the plant for about 15 minutes, then wash the plant off with faucet water.
Biological control is another possibility. Commercially, the “Mealybug Destroyer” ladybug has been imported from Australia to control scale in California citrus groves.
Remember, diligence is needed to control scale. Though any of the methods here may get rid of adult insects, eggs may be unaffected. Repeated control is needed to knock down each new group of hatchlings and any adults that manage to escape.
