STRUCTURE, GROWTH AND ECONOMICS OF INSECTS 



13 



Special Organs of Sense. — The halteres of Diptera contain sensory 

 organs, but their function has not yet been definitely ascertained. 



pron. 



Fig. 18. — Gryllus pennsylvanicus. A, Ventral view of thorax; B, dorsal view of 

 thorax, distal portion of pronotum removed; C, lateral view of thorax and abdomen. 

 Cox., C0X.2, Cox-z, First, second and third coxae; Stl., prosternellum; 5/. 2, 5/. 3, 

 meso- and meta-sternum; Pron., pronotum; £0.2, £5.3, meso- and meta-episternum; 

 Em.2, Em.T,, meso- and meta-epimeron; i, 2, 3, etc., abdominal tergites; 1', 2', 3', 

 etc., abdominal sternites; p., peritreme; S., spiracle; sp., supra anal plate; C, cercus; 

 Ovp., ovipositor; pi., pleuron; Sc.2, Sc.3, meso- and meta-scutum; Scl.2, Scl.3, 

 meso- and meta-scutellum; p.scl., postscutellum; W., W.2, wing bases. 



When deprived of halteres flies cannot maintain their equilibrium in the 

 air. 



