PHYLUM ARTHROPODA 



317 



the hind wing, which are inserted into a trough-like fold in the 

 posterior margin of the fore wing. When flying, the wings act 

 as inclined planes, 

 and locomotion for- 

 ward is attained by 

 both up and down 

 strokes, the tips of 

 the wings moving in 

 a curve shaped like 

 a figure 8. Motion 

 backward, or a sud- 

 den stop, may be 

 accomplished by 

 changing the inclina- 

 tion of the plane of 

 oscillation. 



The abdomen is 

 made up of a series 

 of six visible seg- 

 ments; thin, chitin- 

 ous membranes con- 

 nect the segments 

 and make the move- 

 ment and expansion 

 of the abdomen pos r 

 sible. Each of the 

 last four visible seg- 

 ments of the worker 



FIG. 240. Sting of worker honey-bee, b, barbs 



bears a pair' of wax on darts; /. k, I, levers to move darts; n, nerves; 

 glands. At the end of p ' stin g- fepler ; P& Poison gland; ps, poison sac; 

 " ' sh, sheath; 5th g, fifth abdominal ganglion. (From 



the abdomen of the Packard, after Cheshire.) 



worker and queen is 



the sting, and the slit-like openings of the sexual organs and anus. 



There is no sting in the drone, but a copulatory organ is present. 



The sting is a very complicated structure (Fig. 240). Before 



