294 



EMBRYOLOGY OF INSECTS AND MYRIAPODS 



located at the tip of the stomodaeal invagination, however these cells may 

 be interpreted. 



In the genus Xenos, according to Hoffman (1913), cells from the 

 proctodaeum also contribute to the building up of the mid-gut epithelium. 



When the dorsal organ is much reduced and the dorsal wall closes, the 

 caudal end of the body tends first to straighten (Fig. 232) and then to 

 curve ventrad, so that finally the dorsal surface of the body is directed 

 outwardly (Fig. 233). In the stage shown in Fig. 233 the communication 

 between the mid-gut (ventriculus) and the vesicle-like hind-gut is not yet 



stom 



neurp 



Fig. 

 Dorsal 

 closure. 



232. — Stylops. 

 organ, {drc) 



{br) Brain. {do) 

 Definitive dorsal 



igc) Germ cells, {mge) Mid-gut 

 epithelium, (nc) Nerve cord, (neurp) 

 Neuropile. (proct) Proctodaeum. (stom) 

 Stomodaeum. (y) Yolk. 



i^eurp / rnge 



y 



Fig. 233. — Stylops. (br) Brain, (gc) 

 Germ cells, {mge) Mid-gut epithelium. 

 (neurp) Neuropile. (p) Thoracic legs (dot- 

 ted), (proct) Proctodaeum. (stom) Stomo- 

 daeum. (y) Yolk. 



established. It is probable that the intestine remains imperforate. The 

 development of the mesoderm, which is but feebly represented in Stylops, 

 was not studied by Noskiewicz and Poluszynski (1927). 



The Alfalfa Snout Beetle (Brachyrhinus ligustici) 



The alfalfa snout beetle {Brachyrhinus ligustici) is an introduced 

 species which probably came about forty years ago from central Europe 

 where it is widely distributed. The adult is wingless, which probably 

 accounts for the fact that it has spread so slowly. However, it multiplies 

 in very large numbers in small, restricted areas and does serious damage 

 to alfalfa. It develops parthenogenetically, males not having been found 

 in the United States. 



The egg is in most cases oval in shape but sometimes almost spherical, 

 averaging 0.85 mm. in length. When laid, it is creamy white and is 

 covered with a sticky substance to which the soil particles adhere. After 

 the first day the color changes first to a dull yellow and gradually to a light 



