C. pusio and 

 where found. 



Larva' resist frost. 



Winter dwellings. 



The small larva of Chirononuts pusio has a greenish appearance, 

 lives in a Hydra-like case, and is found in great abundance during 

 the summer months in the Yealm and Erme, two streams flowing off 

 the southern borders of Dartmoor. 



In North Devon I examined the Lynn at Water's Meet in June, 

 1907, but found no larvae in either stream ; possibly they may be 

 found further up the stream. They first appear about the end of 

 March. In 1906 I noted them first on the 2jth and in 1907 on the 

 23rd. By the middle of the summer if the weather is hot the cases 

 are present in such quantities that many of the large moss covered 

 boulders appear quite brown as if with a sediment of mud. Towards 

 the autumn they get scarce again, and by the end of October there are 

 none to be found. Heavy rains causing the river to become swollen 

 seem fatal ; a few days of this treatment, and they are entirely swept 

 away. Whether the flies survive the winter and lay their eggs in the 

 coming spring, I cannot say ; but the fact that flies hatched late in the 

 year do occasionally have the ovaries in a very immature condition is 

 suggestive. But this is not absolutely necessary for the propagation of 

 the species, for the larvae in secluded spots are capable of resisting 

 very severe weather. 



Out of about 20 larvae I put in a dish of circulating water in the 

 autumn of 1906, two at least survived until February i8th, 1907, and 

 during this time a layer of ice formed on the surface more than once. 

 These winter larvae are very inactive, scarcely ever moving far out of their 

 tubes to feed, nor do they grow or develop. I may also mention in order 

 to show the hardihood of Chironomid larvae, that the water in a small 

 vessel containing some large bloodworms was frozen into a solid block of 

 ice, yet on melting the ice the larvae appeared at first none the worse for 

 the severe treatment they had undergone, though they died some days later. 



If some of the larger pebbles be taken up from the bottom of the 

 river during the winter months, a few decrepit cases of the larvae may 

 occasionally be found on the under protected surfaces, and some of 

 these contain larvae which may survive to complete their metamorphoses 

 in the spring. 



