NO. 2 RECOGNITION AMONG INSECTS McINDOO 6^ 



terga. These pouches are lined with hollow hairs into which the 

 secretion from the unicellular glands empties. The same individuals 

 also have a pair of tubular glands lying near the pouches. The same 

 species has a fourth glandular structure lying in the sixth abdominal 

 segment and opening between the sixth and seventh sterna. In the 

 male roach Phyllodromia gennanica the scent-producing organ 

 consists of two double pouches, one of which lies in the articular 

 membrane between the fifth and sixth, and the other between the 

 sixth and seventh abdominal terga. The unicellular glands lie 

 beneath the chitinous lining of these pouches. 



In both sexes of the walking-sticks the secretion from the scent- 

 producing organs is discharged through a pair of pores on the pro- 

 thorax. The glands are paired, are ribbonlike blind sacs with stout 

 walls, and lie in the mesothorax and prothorax. The gland cells 

 certainly lie in the walls of these sacs, although information in 

 regard to this point is wanting. 



In two genera, Eugastcr and Ephippigcr, belonging to the Locusti- 

 dae, reflex bleeding occurs. The liquid issues from a pair of vesicles 

 on the thorax near the bases of the front pair of wings. More infor- 

 mation concerning the source of this liquid is lacking. 



In the male cricket Hadenoccus suhterraneus the scent-producing 

 organ is a pair of appendages protruded from slits between the ninth 

 and tenth abdominal terga. 



HEMIPTERA 



Scale insects emit an odor, but the anatomy of the scent-producing 

 organs has never been studied and the external openings of the glands 

 have never been located. 



In the adult heteropterous Hemiptera, the scent-producing organ 

 is a pair of tubular glands located in the posterior part of the meta- 

 thorax or in the anterior part of the abdomen. The secretion from 

 the glands is emitted through a pair of pores between the bases of 

 the second and third pairs of legs. In Pyrrhocoris apterus a quite 

 complicated organ is found ; here there is a saclike cavity in the 

 metathoracic sternum. A reservoir connects with the sac and a 

 dichotomously branched, collecting tube runs from the kidney-shaped 

 mass of unicellular glands to. the reservoir. 



TRICHOPTERA 



The scent-producing organs of the male caddice fly, Sericostoma 

 pcrsonatum, are the wide maxillary palpi. These appendages give off 

 an odor, but the anatomy of them has not been studied. 



