392 Phylum Arthropoda 



were made to feed the adults and to obtain eggs in captivity but these 

 were unsuccessful. 



Family chironomidae 



METHODS FOR PROPAGATION OF THE MIDGE, 

 CHIRONOMUS TENTANS* 



THE fact that chironomid larvae and pupae constitute one of the 

 staple food items in the ration of nearly all carnivorous young fish 

 has been observed and mentioned by many writers. It has now been 

 observed that chironomid larvae may be reared profitably, in con- 

 junction with Daphnia and other fish food organisms, in small propagat- 

 ing ponds treated with artificial fertilizer and connected with a natural 

 rearing pond for young fish. 



The midge, Chironomus tentans, is well adapted to such propagation. 

 It has many of the characteristics essential to any organism that is to 

 be propagated in such quantities as to render its use as food for fish both 

 desirable and practical. It has a high reproductive capacity. Each 

 female lays one batch of eggs averaging about 2,300 in number, which 

 hatch in about three days at normal summer temperatures. The larvae 

 attain a size sufficiently large for feeding purposes in 16-20 days. They 

 may be reared on plant products which are inexpensive and everywhere 

 easily obtainable. There are at least four generations a year with an 

 overlapping of the cycles which ensures a fairly constant supply of 

 adults and eggs. 



In the vicinity of Ithaca, N. Y., the breeding season ordinarily begins 

 about the last of April and continues throughout the summer and early 

 fall, ending about the first of October. These dates are based on 

 normal weather conditions and seasonal changes, and will vary as they 

 do. The species overwinters in the larval stage. By the time the water 

 has warmed up to io° C. the larvae commence to pupate and shortly 

 thereafter the adults appear. As the water cools down in the fall 

 transformation becomes less rapid and ceases completely about 8° C. 



The rate of mortality during the egg stage is exceedingly low. That 

 during the larval stage is high, and as yet the controlling factor is un- 

 known. The results of several experiments indicate a loss of from 

 about 15% to 30%. The major portion of this loss occurs during the 

 first 8 or 10 days of larval life. 



In general, midge larvae eat whatever is offered them, but under 

 permissive circumstances they do exercise a certain amount of selectivity 



* Abstracted from Cornell University Agric. Exper. Sta., Memoir 173, 1935, by William 

 O. Sadler, Mississippi College. 



