This scale insect attacks the willow, poplar, ash, lilac, and several other ornamental trees and shrubs, besides the apple, and frequently destroys the tree it is on. The scale covering the insect is bluntly pointed at one end, rounded at the other, two or three times as long as broad, and generally more or less bent toward one side, somewhat resembling an oyster-shell in form. It varies in color, but is some shade of gray or brown. During the winter the scale shelters beneath itself the dead female insect which formed it, together with from thirty to one hundred pale straw-colored eggs. These eggs hatch between the middle of May and the tenth of June, according to the latitude, climate and advancement of the season, and the very minute whitish young crawl about seeking for places where they may settle down to feed. When such places are found, they thrust their beaks through the bark and begin to suck the sap from the plant. A scale now begins to be formed over the back of the insect, which becomes adult by fall. The eggs are laid under the scale and the insect dies.

In the more northern states these eggs remain under the scale till the following year, before hatching. Further south they may hatch the same season, giving a second generation the same year.

The fact that the eggs of this pest all hatch at about the same time is made use of in the treatment employed, which is to spray very thoroughly as soon as the eggs hatch - at which time the tiny whitish young can be seen crawling around, if looked sharply for - with linseed oil emulsion, made as follows:

Hard soap, 1 pound

Raw linseed oil, 1 gallon

Water to make 12 gallons

Dissolve the soap in a small quantity of warm water, add the oil and churn by forcing through the spray pump, pointing the nozzle back into the mixture, until it becomes thick; then add the rest of the water, and spray.

It is well to repeat this treatment about ten days later, both because the first treatment may have missed some of the insects and because some of the eggs may not have hatched at the time of the first spraying.