10 



length; they are unsegmented and provided with fine, long hairs. 

 Their function is uncertain, but is probably sensory. The genito-anal 

 orifice is terminal and is controlled by a three-lobed valve, one lobe 

 of which is dorsal and the other two sublateral. In the male the pos- 

 terior margin of the eighth abdominal sternum is produced into a 

 central tooth which is docked at the tip. (See PI. II, fig. D.) In 

 the adult female there are only seven visible ventral segments in the 

 abdomen (see PI. II, fig. E), for the eighth, which is of lighter 

 color than the rest and is not medianty prolonged into a tooth, is 

 hidden by the seventh plate. This sexual difference can be clearly 

 distinguished as early as the sixth instar, when, in the male the 

 sternal tooth appears as a small median knob on the posterior margin 

 of the sternum. 



DEFENSIVE AND STRIDULATING ORGANS. 



When disturbed the changa almost invariably ejects a fetid fluid 

 from the anal orifice. Sometimes this fluid is expelled as a drop, 

 which remains in place, but usually it is ejected to a considerable 

 distance. The fluid itself is colorless or nearly so, but is usually 

 discolored by the presence of soil particles. It is viscid, gives an 

 alkaline reaction, and has a penetrating and unpleasant odor. Ac- 

 cording to Baumgartner (5) it is probably a product of Du Four's 

 organ. All instars secrete this liquid and its use, no doubt, provides 

 a very effective defense against enemies approaching from the rear. 



The stridulating apparatus of the changa is simple. The under 

 surface of the prominent transverse vein of the male tegmen bears a 

 series of transverse chitinized ridges which gives the vein a filelike 

 appearance. The characteristic chirp of the sex is made by " ruffling " 

 the tegmina, so that the inner margin of one tegmen is drawn back 

 and forth rapidly against the filelike vein of the other. The note 

 produced is a short shrill chirp seldom lasting more than two or three 

 seconds. Baumgartner (5) notes the presence of " feebly developed" 

 stridulating organs on the female tegmina and concludes from his 

 observations that the female also chirps. The writer has never heard 

 the female make any note whatever. 



LIFE HISTORY. 



REMARKS ON BREEDING WORK. 



The breeding work with the changa, summarized in this paper, 

 was done in the insectary at Mayaguez, and all statements as to 

 seasonal activity, duration of instars. and the like, are made for that 

 locality only. It is likely that there is not much variation in the 

 insect's life history at different points on the coastal plain, with the 

 possible exception of the drier southern coast. The rainfall probably 



