NUMBER OF EGGS. 



175 



tions iu the course of a year. The female white ant, whose 

 enormously distended body causes her to exceed her compa- 

 nions many hunch'ed times in size, deposits sixty eggs in a 

 minute, which is at the rate of 211,449,600 in the com*se of 

 a year. Other insects are, however, less prolific. The silk- 

 worm produces only from 400 to 500 eggs, the caddice flies 

 less than 100 ; the burying beetles about thirty ; and the 

 horsefly (Hippobosca equina) can only be said to deposit a 

 single egg. 



The eggs of insects are generally of an oval form (fig. 1, 

 oval-spotted egg of the fox-moth), the outer covering being 

 sufficiently rigid to resist ordinary external impressions ; 

 others are, however, soft and pliant. In some species they 

 are globose, as in many Lepidoptera (fig. 2, globular-banded 

 egg of the vapoiu-er-moth) ; or conical, as in the large white 

 cabbage butterfly (fig. 3) ; cylindi-ical, pear-shaped, barrel- 

 shaped, &c. They are for the most part smooth ; but many 

 are very beautiful, ornamented with symmetrical ridges 

 (figs. 3 and 4, egg of the tortoise-shell butterfly), canals, 

 dots, &c., giving them, as Reaumur observed, the appearance 

 of embossed buttons. There are numerous other varieties 

 in the form of eggs, and some are furnished with appendages 

 for peculiar pm-poses. Thus the egg of the dung-fly {Scato- 

 phaga putris, fig. 5) has tw^o oblique props at one end to pre- 

 vent it sinking too deep in the matter upon which it is de- 

 posited ; whilst those of the w^ater scorpion {Nepa cinerea, 

 fig. 10) are furnished with a coronet of spines, forming a re- 



