NA TURAL HIS TOR Y OF MA Y FLIES. 105 



it can be made to live for eight days ; but in 

 its natural state it cannot resist the fatigue of 

 egg-producing. 



Rambur tells us that matrimonial arrange- 

 ments being completed, " the female deposits 

 her eggs simply on the water or on submerged 

 plants, holding herself a little above, and by 

 a quick movement, or else by settling on the 

 plant and plunging her abdomen into the 

 water. She appears to drop her eggs sepa- 

 rately, but as they are sometimes found in 

 masses they must also be thus deposited. 

 The number of eggs must be very consider- 

 able, and in some species may be estimated 

 at many thousands. The larvae would appear 

 to remain about a year to acquire their full 

 growth. The appearance of the perfect 

 insect varies much according to the species. 

 Some are met with throughout the summer 

 season." 



Pictet says : " It is difficult to form precise 

 ideas as to the time which passes from the 

 birth of the larvae to their metamorphosis. 

 Swammerdam gives to the larvae of the 

 Palingenia longicauda a duration of three 

 years, and Reaumur thinks that those of the 

 Palingenia virgo live two years. I have not 

 been able to make direct observation on this 

 subject, because the larvae of the Ephemera 



