214 



FIELD ZOOLOGY. 



so little developed as to be of no use. Eating seems 

 hardly necessary during the extremely short adult life. 



The metamorphosis of the May flies is incomplete. 

 The eggs issue from the egg glands in packets, as the 

 swarm of adults zigzags about over the surface of the 



FIG. 88. Nymph and adult of a May fly, Hexagenia variabilis. A, nymph; B 

 imago. (Natural size. Folsom.} 



water. From the eggs hatch tiny nymphs without wings 

 or wing pads, and looking very much like the most 

 primitive of living insects. These nymphs crawl about 

 over the bottom of the pond, eating any acceptable food 

 that may offer, possibly feeding on other animal life. 

 The mouthparts of the nymph are adapted for biting 



