CHAPTER X. 



WINGS AND FLIGHT. BUZZING AND HUMMING. 



Development of Wings: Nervures, Cells, and Hairs 



— Wings in Diptera : Reasons for Four Wings in 

 Bees and other Hymenoptera — Hooklets — Posterior 

 Wing not ( Flat — Comparison of the Wings of 

 the Sexes — Drone can Fly Backwards — Bee Line — 

 Flapping Movement Converted into Flight : Its 

 Velocity — Experim ent — Forward Flight — Backward 

 Flight: its Necessity ; how Performed — Ascending 

 and Descending Flight — Steering — Wing Rate, 

 Graphic aitd Musical Determination of — Buzzing 

 and Humming — Obturator Apparatus — Tracheal 

 Distension — Specific Gravity — Sonorous Membrane 



— Voice. 



The four membranous wings of hymenopterous insects, 

 articulated in pairs into the meso- and meta-thorax, 

 are formed in the chrysalis from vesicles, or 

 flattened pouches, extravasated or pushed out from 

 the epidermal layer [see Fig. 4), and which are 

 brought into form by a series of interior tubes of 

 chitine, called, in the mature organs, nervines, and 

 seen, in Fig. 27, to divide both anterior and pos- 



