Several kinds of scale insects do serious damage to some of our finest ornamental trees and shrubs, often without the owner being aware of their presence. Now is one of the best (perhaps the best) time of the year to seek them out and get rid of them.
They are on the bark, are usually small, but vary in size - some as small as a pin head, others are as large as a pea. Some are white, and others various shades of brown, and others seem to blend into their environment by nature's protective coloration.
Except fpr the males of some sepecies, adults are permantly affixed in one place. For this reason they are likely to be overlooked until the infected plant is completely encrusted or the twig or other plant part had died.
The mouth (a neddle-like tube) is inserted into the plant and sap is withdrawn. Some of it is exuded as a clear sticky substance called honey-dew. The plant loses vigor, becomes vulnerable to other things which ordinarily would not seriously bother it.
The Bugs are well protected because they live under a waxy, almost impermeable shell. Their eggs are deposited within the shell, affording protection during this stage of development.
One of the easiest and most effective ways to get get of scale insects is to spray them with a dormant oil, such as Scalecide, or Ortho Volck 70 Supreme. Directions on the label for mix and application should be followed closely.
By spraying while the plant is dormant, you can use the oil at sufficient strength to kill scales without danger or injury to the plant.
The oil spray is rated as effective in also destroying scale eggs, immature over-wintering scale adults, aphid eggs, mites and mealy bugs.
The oil should be applied after danger of freezing weather is over but before the buds start to open on trees and shrubs. Do not spray when the temperature is likely to go below 40 during the next 24 hours. It should be applied during the warmer part of the day and preferably when there is little wind blowing.
The oil spray is one of the least hazardous that can be used. It can be harmful if swallowed, but otherwise is not considered dangerous for the applicator or for the pets and wild-life. It smothers the scales.
Your best bet is to check carefully your lilacs, pyracantha, dogwood, apple, tulip tree, privet, spirea, Viburnum, Barberry and other plants. Use a magnifying glass and inspect the bark for abnormalities. The insects will be attached firmly to the bark.
Do not spray just for good luck. It most likely would be a waste of time and money. Spray only if you know you have an infestation and spray only plants know to be infested.