. The American entomologist and botanist. ct our Currant Worm Fly, and the Kosc-bush Sawtly and such few other Sawtlies aspractice similar modes of laying their eggs, tohave no saws at all. For why should natui-e,when she is creating new species, bestow aninstrument upon a particular species which hasno occasion whatever to use that instrument ?In point of fact, however, all female Sawtlies,no matter what their habits may be, possessthese saws, thongli in one genus (Xyeln) thesaws, instead of being hard and horny through-out, are said to be soft and membranous aboveand below;* and in certain o
. The American entomologist and botanist. ct our Currant Worm Fly, and the Kosc-bush Sawtly and such few other Sawtlies aspractice similar modes of laying their eggs, tohave no saws at all. For why should natui-e,when she is creating new species, bestow aninstrument upon a particular species which hasno occasion whatever to use that instrument ?In point of fact, however, all female Sawtlies,no matter what their habits may be, possessthese saws, thongli in one genus (Xyeln) thesaws, instead of being hard and horny through-out, are said to be soft and membranous aboveand below;* and in certain other Sawtlies,though the)^ are as hard and horny as usual,they are degraded and—to use the technicalterm— defuuctionated. This will be seen atonce from an inspection of the following draw-ing (Fig. 10) copied by ourselves fromnature and very highly magnilied. Here arepresents the two saws of the female ofthe AVillow-apple Sawfly (Xi;in<ttus salicis-pomuni, Walsh), which belongs to the very See Westwood s Inlroclucliun, II, ii. O.). same genus as our Currant Worm Fly. Now,we know that the female of the Willow-appleSawfly deposits a single egg inside the leaf ofthe Heart-shaped Willow (Salix cordata) aboutthe end of April, probably accompanying theegg by a drop of some peculiar poisonous afterwards there gradually developsfrom the wound a round fleshy gall, about halfan inch in diameter, and with a cheek as smoothand as rosy as that of a miniature apple; insidewhich the larva hatches out and upon the fleshof which it feeds. Of this gall we propose topresent a figure to our readers in the next num-ber of our Magazine, in illustration of a SecondArticle on Galls and their architects. Inthis particular case, therefore, as the femaleFly requires a complete saw with which to cutinto the Willow leaf, nature has supplied herwith such saws, as is seen at once from Figure10, a. Now look at Figure 10, b, which is anaccurate representation under the microscopeof the two
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Keywords: ., bookcen, bookdecade1870, booksubjectbotany, booksubjectentomology
