180 Bugs, Cicadas, Aphids, and Scale-insects 
scrubbed with a carbolized solution of soft soap (soap io parts, carbolic 
acid 2 parts, water 88 parts) and carbon disulphide injected into the soil about 
the base of the tree. 
Of the various aphids which attack foliage trees, the most familiar are 
those which resemble the woolly apple-aphis in their habit of secreting floc- 
culent masses of wax, and thus obtain the name of “ blight,” as elm-blight, 
beech-blight, alder-blight, etc. The alder-blight, or woolly alder-aphis, 
Pemphigus tessellata , gives birth in autumn to vast numbers which crawl 
down the trunks to the ground, where they congregate in the crevices between 
the base of the trunk and larger roots and the soil, or beneath the fallen leaves 
or other rubbish at the surface. They remain in their hiding-place until 
spring, when at the coming of the first warm days they crawl up the tree 
and out to the budding tips of the twigs. Here they begin sucking sap and 
at the same time secreting waxen “wool.” In a week or so they become 
mature and begin giving birth to living young, and hereafter during the 
autumn and summer agamic generation after generation is produced. With 
the oncoming of cold weather the last generation crawls down to the ground 
to seek winter quarters. No sexual forms of this species have yet been 
found. 
Among the gall-forming aphids, one of special interest, because of the 
strange character and abundance of its galls, is the cockscomb gall-louse, 
Colopha ulmicola. Elm-trees infested by this aphis develop on the upper 
side of the leaves narrow, erect, blackish galls irregularly toothed along 
the top, and suggesting a cock’s comb sufficiently to warrant the common 
name. These aphids secrete much honey-dew, noticeable on sidewalks 
under the trees and on the leaves, and in this honey-dew where it covers 
the galls and leaves grows a blackish fungus. 
Of all the families of the Hemiptera, probably the most important from 
the economic entomologist’s point of view is that of the Coccidae, or scale- 
insects, and from the point of view of the biological student, also, no other 
is more interesting and suggestive. More nearly on a footing with the 
Coccids than any other Hemiptera are the Aphididae, just studied, but the 
scale-insects are even more specialized in curious and unusual ways, both 
as regards structure and physiology. In the more specialized scale-insects 
the females are quiescent in adult life, as well as in part of the immature 
life, and their fixed bodies are very degenerate, lacking both organs of loco¬ 
motion and of orientation, viz., eyes, antennae, wings, and legs. The family 
is a large and widely distributed one, numbering about 1450 known species 
in the world, of which 385 occur in the United States, but almost all are 
small and obscure and so foreign in appearance to the usual insect type 
that but few others than professional entomologists and the harassed fruit¬ 
growers ever recognize them as insects. Most of us have often had oppor- 
