3i8 NATURAL HISTORY OF AQUATIC INSECTS CH. 



females could hardly meet before their brief life was 

 ended. To some allied species, which emerge in 

 scanty numbers, a longer span has been conceded. 

 One such Ephemera I kept alive for six or seven 

 days, and it might have lived longer had it not 

 been restrained from flying abroad."^ [Here ends 

 Reaumur's account.] 



De Geer supplements the observations of Reaumur 

 by a number of interesting particulars. In Sweden, 

 where he lived, the prodigious swarms of Ephemeras 

 do not occur, though many species are found in 

 smaller numbers. 



The first kind which he describes is Ephemera 

 vulgata, whose larva is very common in ditches, 

 ponds and slow streams, where it burrows in the mud 

 or hides beneath stones. It can walk on the bottom, 

 and also swims at times, drawing up the legs, and 

 propelling itself by an up and down movement of the 

 abdomen. The larval antennae are rather long, and 

 the slender mandibles (which are crossed) extend 

 considerably in front of the head. There are six 

 pairs of tracheal gills, which extend over the back 

 and point towards the tail ; each consists of a double 

 leaflet fringed with long, hollow filaments, in which 

 fine air-tubes run. The legs are flattened and fringed 

 with hairs. The three tail-filaments are longer than 

 the body, and each is fringed with hairs on both 

 sides. [In some species — e.g. Chloeon dipterum and 



^ Observations and experiments made since Reaumur's time 

 render it probable that the life of an Ephemera may be pro- 

 longed by captivity. Mating and egg-laying seem to hasten 

 the end. 



