76 Farmers’ Bulletin 1169. 
Habits —The adults emerge from hibernation about the time box- 
elder buds open and lay their eggs (fig. 54, a), usually in crevices of 
the bark of this favorite host tree. The hatching young migrate to 
the foliage in great hordes, traveling up and down the trunk. After 
several molts (fig. 54, b, ¢, d) maturity is reached and by fall great 
streams of the bugs start on the march for winter shelter. 
Iemedies—Spray trees as soon as the insects appear with soap 
solution (p. 14) or kerosene emulsion (p. 12-13). In the fall great 
masses of them can be destroyed by pouring hot water or kerosene 
on them or by sweeping them into a vessel containing kerosene. 
SCALE INSECTS IN GENERAL. 
Appearance and habits.—Scale insects are so called because of the 
scale that covers or constitutes the back of most of them. This 
covering may be horny, leathery, waxy, cottony, or mealy, and just 
as various in size, shape, and color. There are many species of scale 
insects; and, according to the consistency of their covering, they are 
roughly divided into armored scales, soft (leathery) scales, cottony 
scales, mealybugs, etc. Except for a few days after hatching, when 
they are naked, these insects are nearly always covered by the scale 
characteristic of the species to which they belong. The number of 
generations annually, date of hatching, and other life-history habits 
vary with the species, season, and location. They are all plant 
feeders, some confining themselves to a single species of plant, while 
others occur on a great variety of plants. They occur on roots, main 
stems, branches, and twigs; some of them occur also on the leaves and 
fruit insummer. They feed on sap, which, by means of their slender, 
flexible, needlelike beaks, they suck up from within the plant tissues. 
They are, therefore, classified as sucking insects. Some of them pro- 
duce more or less honeydew, which attracts ants, bees, wasps, etc., 
which eat it but do not harm the plants. Certain fungi growing on 
honeydew frequently give the affected plants a sooty appearance. 
Natural control.—Like other insects, most scale insects are usually 
kept in check by a variety of natural agencies, especially parasitic 
and predacious insects. Under such conditions they do no perma- 
nent serious harm and require no remedial treatment. Quite often, 
however, some species become so numerous as to be very injurious, 
and make early treatment imperative if the life of the affected plant 
is to be saved or its value kept unimpaired. 
Remedies—Winter spraying with a contact insecticide (p. 11-14), 
done when the buds are dormant, is preferable for scale insects 
because (1) there is then no delicate foliage to injure and none to 
conceal the insects or to use up the spray; (2) dead and superfluous 
portions of the plant may and should then be removed, still further 
reducing the area to be sprayed and exposing the insects; (3) plants 
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