Identifier: introductiontozo00dave Title: Introduction to zoology; a guide to the study of animals, for the use of secondary schools; Year: 1900 (1900s) Authors: Davenport, Charles Benedict, 1866-1944 Davenport, Gertrude Anna Crotty, 1866- Subjects: Zoology Publisher: New York, Macmillan company London, Macmillian and co., ltd. Contributing Library: MBLWHOI Library Digitizing Sponsor: MBLWHOI Library

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Text Appearing Before Image: 07. 40 ZOOLOGY species of insect on one kind of tree are quite similar,but if the same insect stings another species of tree, adifferent kind of gall is produced. Also when differentspecies of gall-wasps sting one and the same leaf, the gallswill be unlike. Hence the characteristic form of the gallis determined both by the species of plant and by the species of insect whichlives in it. It is interest-ing to collect galls, watchfor the emerging Avasps,determine their species,and thus get their entirelife history. The gall-wasps are, on the whole,injurious to agriculture. The plant-eating Hy-menoptera are extremelydestructive pests. Theyoung are known asslugs, from their re-semblance to the trueslugs, which are snail-likeanimals. They infest peartrees and rose bushes, leaving scorched, dried leaves behindthem.1 Here also belong the currant-worm and the saw-flies (Figs. 39 and 40;, which eat leaves like caterpillars,but differ from them in having twelve or sixteen prolegsinstead of ten.

Text Appearing After Image: FIG. 40. —Eggs of Nematus, a saw-fly ongooseberry leaf. Photo, by V. H. L. 1 See The Pear Slug, in Circular No. 26, 2d Series, U. S. Depart-ment of Agriculture, Division of Entomology. APPENDIX TO CHAPTER II 41 APPENDIX TO CHAPTER II KEY TO THE PRINCIPAL FAMILIES OF LEPIDOPTERA ai. Antennae club-shaped at apex ; wings when at restheld vertical (Fig. ID) «.2. Antennae usually having the form of a bristle, spin-dle, or thread, often with a comb ; wings at restheld out flat (Fig. 23), or else folded over bodylike a gable roof (Fig. 25).l>i. Hind wing usually with one or two dorsal veins [Macrolepidoptera, large-winged moths].Ci. Antennae spindle-shaped or keeled, rarelyclub-shaped ; wings small ; dusk fliers.d\. Antennae prismatic .... do. Antennae not prismatic, but e\. attenuated at end, occasionallypectinate .... /!. Clear winged (Sesiina).f.2. Wings speckled, antennaemuch longer than head(Cossina)./3. Antennae hardly longer than head (Hepialina). BO. club-shaped, occasionally p

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