THE AMERICAN ENTOMOLOGIST. 



45 



OALLS AND THEIR AR.0mTE(:TS-2(l ARTICLE. 



In our forinei- Article upon tliis very inter- 

 esting and instrnctive subject*, we shoTved that, 

 in the language of Naturalists, " Galls" are all 

 such deformations of living and growing plants, 

 as are produced by one or more insects or other 

 allied animals residing therein, and deriving 

 their nourishment therefrom. We further 

 showed that galls were of the most various 

 sizes, shapes and colors; that the same gall 

 almost invariably grows upon the same part of 

 the same plant, whether that part be the flower, 

 the twig, the branch, the root or the leaf; that 

 for the formation of a gall the combined action 

 of an animal and vegetable organism is abso- 

 lutely necessary; that the insects which are 

 known to be the architects of galls are by no 

 means an isolated group, but belong to several 

 diflereiit Families in no less thau five different 

 Orders; that in none of these Families is the 

 gall-making facnlty universal, the very same 

 genus often containing certain species that 

 make galls and certain others that do uot; and 

 finally that, besides the true Insects, many of 

 the Mites, which are uot true Insects, construct 

 galls of no very conspicuous size, shape or 

 structure. 



We then went on to state that Galls originate 

 in two distinct modes, either first, by the mother 

 >lisect depositing one or more eggs in or ou the 

 part of the plant which she attacks, or secondly, 

 oy a young larva stationing itself upon a leaf or 

 father part of a plant and irritating its surface 

 with its beak, until a hollow sack is gradually 

 . formed, inside which the larva finally develops 

 and j)ropagates. In the former case, when but 

 a single egg is deposited in one place, the larva 

 that develops from that egg forms but a single cell, 

 as in Figures 30, 31, 32 and 35 of this Article, and 

 the gall is then technically said to be "monotha- 

 lamous," i. e. one-celled; but wherever several 

 eggs are deposited in one place, the larvas devel- 

 oping therefrom inhabit several cells enclosed in 

 a common envelop, as in Figures 83 and 3i of this 

 Article, and the gall is then technically said to 

 be " polythalamous," i. e. many-celled. In the 

 second group of galls, namely those originated 

 by young larvre, the inhabitants of the gall, 

 however numerous they may be, always reside 

 promiscuously in the same large cell or hollow. 



In addition to the history of the difTerent 

 Galls treated of in our former Article, we will 

 now give a brief account, illustrated by Figures 

 drawn from nature, of several others of our 



commoner galls, grouping them according to 

 the different Families to which the diflerent 

 gall-makers belong. 



Galls made l)y Sawflies. 



(Order Ilymenoptera , Tenthredo F.imily.) 



The Willow-apple Gall (Salicis pomum, 

 Walsh), repi'csented in Figure 30 is of a green- 

 ish yellow color, usually with a bright rosy 

 cheek, and has very much the look of a miuia- 

 tui-e apple. It makes its first appearance early 



[Fig. 30.] 



'Amkeican Entomologist, Vo 







Colors — Piilc-gi-een and rosy, 



in the spring, on the leaf of the Heart-leaved 

 Willow (Sallx cordata) — nearly attains its full 

 size by the last of May, when the rosy cheek is 

 already very conspicuous — and is fully matured 

 by the last of July. Internally it is of a fleshy 

 consistence and whitish color like any ordinary 

 apple. But appearances are sometimes very 

 deceptive. Though this gall looks as tempting 

 to the eye as a cherry, it is tasteless and insipid 

 when taken into the mouth. That is, it is taste- 

 less and insipid to us human beings ; but no 

 doubt, to the little larva that bores into its sub- 

 stance and feeds throughout its entire larval 

 existence upon its pulp, it offers as relishing a 

 flavor as would a basin of the best Turtle Soup 

 to a hungry Alderman. 



The four-winged fly that originates this gall 

 {Neniatus s. iwmum, Walsh) presents very 

 much the appearance of the Imported Currant 

 Worm Fly which we figured ou page 16 (Fig. 

 7, a ^,b ?), except that it is about ouc-third 

 smaller. We have reared hundreds of them 

 from the gall, and so variable are they both in 

 size and in coloration, tliat a suite of specimens 

 which by way of experiment we sent to Mr. 

 Noi-ton of Connecticut — an Entomologist who 

 has devoted years of his life to the special study 



