THE LOCUST 



159 



segmented feeler, the palp, which is an organ of chemical sense; (2) 

 the galea, a curved part with a rounded end; (3) the lacinia, a curved 

 part which ends in sharp, black teeth. The labium has a basal portion, 

 which bears right and left palps, which are sensory in function, and 

 a flattened median portion which is partially divided into right and 

 left halves. The labium is in reality composed of right and 



Fig. 69. — Mouthparts 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 the simpler mandibulate types with jaws and 

 other parts, such as are found in cockroaches and locusts. A, labrum. 

 B, mandibles. C, hypopharynx. D, first maxillse, each with basal portions 

 (s and c), lacinia (/), galea {g and sg), and palp {mp and pf). E, labium, 

 or fused second maxillae, with basal portions {sm and m), glossa {g and pg) 



and palp {Ip). 



(From J. W. Folsom, "Entomology," copyright, 1906, by P. 

 reprinted by permission.) 



Blakiston's Son and Co., 



left appendages, which have become partly united in the median line. 

 Remove the right maxilla by grasping it at the base with forceps and 

 carefully pulling it away. Remove the entire labium in the same 

 manner. Removal of these parts exposes the hypopharynx, or tongue, 

 which is an important organ in the ingestion of food. The space sur- 

 rounded by the mouthparts and from which food enters the esophagus 

 is known as the buccal cavity. Draw these removed mouthparts 

 (X 10), orienting with the former attached portions toward the top 

 of the page. 



