180 Bugs, Cicadas, Aphids, and Scale-insects 



scrubbed with a carbolized solution of soft soap (soap 10 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 Coccidas, 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- 



