ARTHROPODA. 



257 



269. Comparative Study of Insects: a Practical Exer- 

 cise for Library and Field. Make a table similar to that 

 on the preceding page, for a representative of each of the 

 principal groups of insects. Include in it the principal 

 points of similarity and contrast that you can discover. 



FIG. 102. Mouth parts of a cockroach (biting). A, upper lip (labrum); B, 

 mandibles or jaws proper; C, hypopharynx; D, maxillce, or under jaws; E, under lip or 

 labium. From Folsom. 



Questions on the Figure. By study of other texts determine the 

 function of these various structures. Compare with the next figure. 



The following will be good animals although others just 

 as good may be found by the student: the grasshopper; 

 the June-bug or other beetle; a dragon-fly; a water- 

 boatman; the cicada or the squash bug; a butterfly; a 

 fly or mosquito; a bumble bee; an ant. Among other 

 things, the following points should be worked out : 



