22 



Outline of Life- history 



small, 

 to five 

 on the 



No complete resting- stage ; the pupa lasts three 

 days. Fly short lived ; lays the eggs all together 



margin of a stream. 



Fig. i3.—Sfratiomi/s rhamacloon. i, larva. 2, larva floating at sixrface of 

 water. 3, larva descendiug. 4, pupa within larval skin. 5, head of larva, 

 dorsal view {a a marks the attachment of the thoracic integument). 6, head of 

 larva, ventral view. The ventral wall is incomplete behind, and the pharynx 

 and gullet arc exposed. 7, piece of integument. 8, ditto, in section, with conical, 

 calcareous nails, q, a single calcareous nail (surface view). 10, spiracle, lying in 

 centre of tail-coronet. (From Miall's Natural History of Aquatic Imccts. 2. ^, 

 and 4 are copied from Swammerdam ) 



3. Stratiomys (fig. 13).— Larva fairly active, but only 

 in rising and sinking ; feeds on microscopic organisms. 



