The May-Flies or Shad-Flies 



word, ephemeral. But they live longer than a day. They do 

 not eat, since, as we have stated, the mouth-parts are atrophied 

 and the alimentary canal is not fitted for the digestion of food; 

 but it has been shown that where the air is not too dry some of 

 them can live for several days. It is stated that Curtis kept one 

 alive for three weeks; but in general they die within three or 

 four days, and frequently in a few hours, or even less time. The 

 males are readily distinguished from the females from the fact 

 that with the males the hind legs only are atrophied or feeble, 

 while with most females the fore legs as well as the hind legs are 

 too feeble to support the body. When at rest the front legs are 

 generally extended straight in front of the head, and frequently 

 very close together, the anal setae usually slanting upwards. As 

 a rule they remain quiet during the day, limiting their flight to 

 the cooler hours of sunlight or extending it later in the evening, 

 just after sunset. Where there is a strong artificial light they will 

 fly until late in the night. The numbers in which these creatures 

 swarm are often extraordinary. I drove through a dense cloud 

 of them once on the banks of the St. Lawrence River in the 

 month of June when both the air and the ground and our 

 clothes looked as though the heaviest kind of a snow-storm were 

 raging. Along the shores of the Great Lakes their bodies are 

 frequently massed in great windrows miles in length and of a 

 very considerable thickness. 



Most of them couple during flight, the male undermost. 

 Egg-laying is usually performed in fresh water, though one exotic 

 species lays in brackish water. The females of some species dis- 

 charge the contents of their ovaries at once in the form of a pair 

 of egg-clusters. These upon reaching the water rapidly disinte- 

 grate, and the eggs sink to the bed of the river or stream. 

 Others drop their eggs gradually, a few at a time, the female 

 either alighting on the surface of the water at intervals to wash 

 off the eggs that have issued, or she creeps down into the water, 

 enclosed within a film of air, to lay her eggs on the under side of 

 stones, after which she floats up to the surface and either flies 

 away or is drowned. In one case a female has been seen to 

 deposit living larvae. 



These insects can readily be bred in fresh water aquaria, but 

 Eaton says that it is important not to grow Ranunculus in the 

 aquaria, because the sap exuding from its broken stems appears 



378 



