98 OUR INSECT FRIENDS AND FOES 



of the members of a species within a certain 

 area will reach maturity almost simultaneously. 



Although the perfect May-flies are such 

 familiar insects, much still remains to be 

 accurately observed and recorded concerning 

 the length of time occupied by the larval and 

 nymphal stages. These early stages are spent 

 entirely in the water, and appear to last for two or 

 three years, during which time several moults or 

 casting of the skin take place. The larvae are 

 curious looking creatures, and easily recognized, 

 their mouths are well developed, and many ol 

 them seem to be exceedingly predaceous in their 

 habits. While some species in the larval stage 

 lead an active life crawling about amongst the 

 debris at the bottom of the stream or pond, 

 others make remarkable chambers with double 

 openings, so that they can enter from either end, 

 in the mud of submerged banks. The larva has 

 a somewhat flattened body, tapering at each end, 

 long bristle-shaped antennae, two or three long 

 plume-like bristles at the extremity of the body, 

 and a series of paired branchial leaflets attached 

 to the sides of the abdominal segments. The 

 nymph resembles the larva in general appear- 

 ance, except that wing-cases containing the 

 developing wings of the perfect insect are 

 present on the thorax. This nymph in due 

 course quits the water, and very shortly after 

 there emerges from it what at first appears to 

 be the perfect insect, but which, although able 

 to use its wings sufficiently to fly a short dis- 

 tance to some suitable resting-place, is not really 

 quite perfect, for all its parts are covered by 



