886 



AN INTRODUCTION TO ENTOMOLOGY 



typical hymenopterous wing; in the former the veins are lettered, in 

 the latter, the cells. These are figures of a fore wing of Pamphilius 

 (Fig. 1 13 5) except that vein R2, which is lacking in this genus, is 

 added. This vein is well preserved in Macroxyela (Fig. 1134); but 

 in Macroxyela vein Cu2 is lost; the position of the last forking of the 

 cubitus is indicated, however, by a bend in this vein. In these figures 

 of the typical hymenopterous wing the lines indicating the course of 

 the free part of media, after it separates from radius, are crossed by 

 short lines. 



The cells marked m, m, m, in Figure 1 127 are termed the marginal 

 cells; and those marked sm, sm, sm, sm, the submarginal cells; the 

 three cells, M4, ist M2, and M3 are termed the discal cells. 



The working out of the various ways in which the wing-venation 

 has been reduced in the more specialized families is an exceedingly 

 difficult problem, one that is beyond the scope of this book. A general 

 discussion of it has been published by the writer (Comstock '18); 

 a special paper on the venation of the Chalastogastra has been pub- 

 lished by Professor A. D. MacGillivray ('06); and a very detailed 

 account of the modifications of the wing-venation in the Clistogastra 

 has been prepared by Professor J. C. Bradley and will probably soon 

 be published. 



The mouth-parts are formed for chewing in all 

 Hymenoptera, and in the more specialized members 

 of the order they are fitted for both chewing and for 

 sucking or lapping liquid food. In the saw-flies, for 

 example, the mouth-parts resemble quite closely the 

 orthopterous type, while in the bees they differ 

 markedly from this type; and intermediate forms 

 exhibit intermediate degrees of modification of the 

 mouth-parts. 



In the long-tongued bees the labrum and man- 

 dibles retain the form characteristic of chewing in- 

 sects and the mandibles function as organs for crush- 

 Fig. 1 128.— Head ing or cutting ; but the labium and maxilljE are elon- 

 of a honey-bee: gated, the maxillcB form a sheath to the labitim, the 

 a, antenna; c, ^hj-gg organs thus constituting a suctorial apparatus 

 clypeus; M, lab- f^- ^ ^^ j .,. r- l^u -n 



rum; m, man- (^^S- 1 1 28). In this figure the maxilla? are repre- 

 sented separated from the labium. 



The legs of the H^Tnenoptera present characters 

 that are much used in the classification of these in- 

 sects. Among the more strildng of these are the fol- 

 lowing ; the trochanter may consist of two segments 

 (Fig. 67,6) orof only one; the metatarsus of thehind 

 legs is greatly enlarged in bees (Fig. 67, C); and in several families 

 the fore legs are fitted with an organ which is used in cleaning the 

 antenncc, the antenna cleaner or strigilis. This consists of a curved, 



dible; mx, max- 

 illa; p, labial 

 palpus; /, la- 

 bium. 



