96 DIPTERA. 



pendicular, the deserted part of the sheath lies 

 upon the water like a boat, while the body of 

 the insect may be compared to the sail and 

 mast. At this moment the animal is in con- 

 siderable danger; for, should the slightest wind 

 arise before the gnat can disengage itself, the 

 water enters the boat, it sinks to the bottom, 

 and the insect is infallibly drowned. Thus, in 

 those days of transformation when the wind 

 blows and the water is ruffled, thousands of | 

 gnats meet their death in that very element, 

 without which, but a moment before, they could 

 not have existed. When no such accident oc- 

 curs, the body speedily dries, the tail is detached 

 from the sheath, and the gnat flies into the 

 air. 



Instinct directs the fecundated female to re- 

 turn to the water, and prepare for the welfare 

 of a future progeny, whose existence she will 

 never live to witness. For this purpose she 

 fastens herself by her four first feet to a floating 



o 



leaf, or other substance, and crossing her hind 

 legs, places in the angle thus formed, her first 

 egg with the end of her tail, which in these in- 



