. The American entomologist. Entomology. THE AMERICAN ENTOMOLOGIST. 103 the formation of galls is the exception, and tliat the first mode, nunioly that when the mother insect deposits one or more eggs on or in the infested plant, is (ho rule. In the latter ease, when bnt a single egg is deposited in one place, the larva that develops from tliat egg forms bnt a single cell, inside whicli it resides, as 78 a. The gall is (hen teelinieally said to be •• ; i. c. one-celled. lUit when- ever several eggs are deposited in one place, the larvie developing therefrom inhabit s
. The American entomologist. Entomology. THE AMERICAN ENTOMOLOGIST. 103 the formation of galls is the exception, and tliat the first mode, nunioly that when the mother insect deposits one or more eggs on or in the infested plant, is (ho rule. In the latter ease, when bnt a single egg is deposited in one place, the larva that develops from tliat egg forms bnt a single cell, inside whicli it resides, as 78 a. The gall is (hen teelinieally said to be •• ; i. c. one-celled. lUit when- ever several eggs are deposited in one place, the larvie developing therefrom inhabit several cells enclosed in a common envelope, as in Fig. 8.'i, b. The gall is then said to be '• polythalamons," i. e. many-celled. In the second group of galls, namely those made by Plant-lice. Mites, etc., the inhabitants of tiic gall, however numerous lliey may be, always resiile in'omisc-nously in the same large cell or hollow. The number of galls formed by distinct spe- cies of insects or mites upon various plants in -Vmerica is very great, and a large proportion of them are as yet undescribed and unknown to science. Of those (hat occur upon trees and shrubs, exclusively of herbaceous plants, we are ourselves acquainted with nearly two hundred different species, about a third part of which are undescribed. In the following paragraphs, we propose to give a brief account, illustrated by tigures, of some of the more conspicuous ones out of the whole number, made by three dif- ferent Families of insects, namely the Gall-dies, the Gall-gnats, and (he Plant-lice. (ialls made Ity Gall-flies. ((>«/>«.) TuE Tkue ''Oak Aitle," as it is popularly termed, (Quercus sjjoi)(/(/ira. Osten Sacken, Fig. 78) occurs exclusively upon (he Black oak (Quercus (inctoria). It commences its growth in May, or as soon as the \oung leaves put forth, [fit;. 78.]. (-'—ln-ab inHiile: Jello\vi^^h-b^o\vn and reaches its full size in a few weeks. The central cell (Fig
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectentomology, bookyear1
