12 



O III line of Life-history 



' Larvae about to pupate have the thorax much swollen. 

 The pupal stage is passed in a gelatinous case, wliich 



Fig. 4. — Larva of CJiironomus minutus. 14, hooks on prothoracic appendages. 

 5, 6, hooks on anal appendages. 



adheres to a stone in the stream (fig. 5). The wall of 

 the case is structureless, but seems to have a fibrous 

 texture within. At each end of the case is a spout-like 



Fig. 5. — Pupa of Chironomus minutus, lying in its transparent sheath. T]ie 

 arrows show the current of water. >, 15. 



aperture, and by the undulations of the body a constant 

 current is kept up, flowing in at the fore aperture, and 

 out behind. The head of the pupa lies in a part of the 



