•58 



ENTOMOLOGICAL NEWS. 



[March 



Fig. 1. — Upper side of posterior seg- 

 ments of abdomen, showing position 

 of sound-producing organ. 



THE SOUND-PRODUCING ORCANS OF LEMA TRILINEATA. 



By C. M. Walkek, Amherst, Mass. 



"When Lema trilineata is irritated or disturbed in any way it 

 makes a curious shrill, squeaking sound, and if the insect be 

 carefully watched, it may be 

 observed that in producing 

 this sound the tip of the ab- 

 domen is raised and vibrated 

 very rapidly, causing it to 

 move back and forth against 

 the underside of the elytra. 

 Upon examining the struc- 

 ture of the parts concerned, 

 a hard horny area was found 

 on the dorsum of the last 

 segment of the abdomen 

 (Fig. 1), composed of regular transverse ridges and divided by 

 a median depression. This hard chitinous area is somewhat 

 triangular in shape 

 with the base at the 

 middle of the ante- 

 rior margin of the 

 segment and the 

 rounded tip near 

 the middle. There 

 are numerous hairs 

 and spines[scattered 



over the remaining fig. 2.— upper side of posterior segment of abdomen, 



portion of the seg-^^°^*^^^**"°^'P''°**"^*"^*^''^*°' 

 ment (Fig. 2). 



With the aid of the compound microscope each elytron, 

 especially on the tip and along the inner edge, was found to 

 be covered with short spines directed posteriorly. The spines 

 appeared to be of two kinds. Those along the extreme edge 

 were larger and longer and fewer in number than those just 

 back of the edge, which were of the character of modified 

 scales. These scales were more or less flattened and were 

 elevated at a slight angle, as seen when observed laterally. 

 In order to produce the sound the beetle raises the end of the 



