12 



show some movement of the mouth setae. When examined from the 

 dorsal side with transmitted light, living specimens usually show more 

 or less movement of their internal organs. More satisfactory exami- 

 nation can be made with a hand lens several days after the treatment, 

 when the dead insects are brownish in color. 



The Greenhouse Aleyrodes, Aleyrodes vapora- 



riorum Westw. 



DESCRIPTION. 



Egg. (Plate II, Figs, i and 2.) 



The egg is irregularly ovoid, the apical end being the more 

 pointed, and one side more or less flattened. On the basal end, 

 usually a little to one side of' the center, toward the more rounded 

 side, is a short, slender stalk, which is inserted in the leaf. The 

 length of the stalk varies from one-fourth to one-eighth the length of 

 the egg, its diameter being about .01 mm. Its form varies, being 

 seemingly determined by the epidermal cells of the leaf between 

 which it is inserted, and it is frequently encircled near its base by a 

 transverse ridge. Color of egg when first laid, light yellowish green, 

 glistening ; chorion very soft and delicate, somewhat viscid. The 

 eggs are translucent at first, but gradually become darker, until 

 finally, after two or three days, they are opaque. At this time the 

 chorion has become quite hard, and it is difficult to detach an egg 

 from the leaf without injuring it. In the course of a few days the 

 egg, by contact with the adults, usually becomes more or less covered 

 with a flour-like substance. Parts of the egg not so covered appear 

 of a metallic bronze color. The surface of the egg is unmarked, but 

 within and usually about in the center, may be seen a rounded, 

 orange colored body, surrounded by colorless yolk globules. The 

 developing embryo can be plainly seen. 



The length of the eggs, exclusive of the stalk, varies from .187 

 to .236 mm. ; the greatest transverse diameter varies from .077 to 



