346 



THE LOCUST 



variously modified in different parts of the body in correlation 

 with special functions. There is typically a pair of jointed 

 appendages for each of these somites, although these may be 

 absent in certain regions, and the body is completely covered by 

 the exoskeleton. 



The appendages of the head consist of a pair of sense-organs, 

 the antennoe (cf. Fig. 168), and three pairs of oral appendages. 



Fig. 170. — Mouth parts of a cockroach, Ischnoptera pennsylvanica. 



Mouth parts of insects show great diversity of structure in relation to feeding habits- 

 All seem to have evolved from simpler types with jaws and other parts such as are found 

 in cockroaches and locusts. 



A, labrum. B, mandible, C, hypopharynx. D, maxilla with basal portions (s and c), 

 lacinia il), galea {g and sg), and palp (mp and pf) . E, labium with basal portions (m and 

 sm), glossa {g and pg) and palp (Ip). (From Folsom, "Entomology," copyright, 1906, by 

 P. Blakiston's Son and Co., reprinted by permission.) 



The compound eyes are primarily sense-organs, and not appen- 

 dages modified for sensory functions as are the antennae. What 

 are called the mouth parts of the locust {cf. Fig. 170), include the 

 following: an upper lip, or labrum, which is not formed by the 

 fusion of right and left appendages as might be supposed; a pair 

 of appendages known as the mandibles, which are the strong biting 

 jaws on either side of the mouth; a tongue-hke projection, the 

 hypopharynx, which, like the labrum, is a single median structure 



