20 
BULLETIN OF THE BUREAU OF FISHERIES. 
Food of 52 Hydrous larvse taken from pond at Fair port, Iowa. 
[The figures indicate percentages, the entire food being 100.] 
From a study of this table several facts stand out quite clearly. 
1. The chief food of the Hydrous larva consists of snails and Chironomus 
larvae; a mere glance down the first two food columns is convincing proof of this. 
Nineteen of the 52 specimens had eaten nothing else, 3 others had eaten only 
Chironomus pupae in addition, and in 4 others these two foods constituted 90 to 
98 per cent of the total eaten. In other words, half of the larvae had lived entirely 
upon snails and Chironomus species. Only 2 out of the entire number are credited 
with having eaten none of these two foods. It is also worthy of note that 4 of those 
that had eaten nothing else were fully grown. 
