348 THE NEMOCERA. 



Notwithstanding the disagreeable associations con- 

 nected with these insects, there are several points in 

 their natural history of great interest. During their 

 preparatory states they are strictly aquatic, and the 

 female, when about to lay her eggs, seeks the water, 

 and resting upon its surface, attaches the eggs to 

 each other in such a way as to form a small concave 

 raft, which then floats securely until the young larvae 

 are ready to emerge. These are curious little worm- 

 like creatures, furnished with a rounded head, and 

 with the body divided into distinct segments, from 

 the last but one of which springs a singular tail-like 

 tubular organ, terminated by a little five-rayed star. 

 This is the respiratory organ; the larva places the 

 aperture at the surface of the water and expands the 

 star, which then prevents the water from getting into 

 the tube, and in this way the little creatures may 

 often be seen suspended at the surface of standing 

 waters. It is not confined to this position, however, 

 for it can descend in the water and swim about by a 

 jerking movement, but before quitting the surface it 

 closes the aperture of its respiratory apparatus by 

 folding in the rays of the star. 



In this way the larval period of existence is passed, 

 and after changing its skin several times, the insect 

 undergoes its change to the pupa state. It continues 

 active, but is incapable of taking any nourishment, and 

 as it still requires to keep up a communication with 

 the air for the purpose of respiration, this is effected 

 by the agency of two tubes, attached, not to the ex- 

 tremity of the abdomen, but to the thoracic segments, 

 so that the position of the animal in the water is 

 completely changed, and it now floats with its head 

 upwards when engaged in breathing. The anterior 



