Chironomidae 395 



The correct amount needed for treating a pond may be determined 

 only approximately because of the limited data at hand. Often two 

 ponds equally fertilized and run parallel show a wide variation in 

 production. It appears that the best results were obtained with soy- 

 bean meal used at the rate of 2% pts. to 100 cu. ft. of water. The method 

 of administering the fertilizer which has proved the most satisfactory 

 is that of starting the pond with 1 to 1% pts. of the fermented meal per 

 100 cu. ft. of water and then fertilizing again at the rate of 1 pt. per 

 100 cu. ft. of water when the culture begins to clear up — that is, when 

 the green color, due to the presence of microscopic algae, begins to dis- 

 appear. This happens usually 6 to 10 days after the culture is started, 

 but it varies greatly with different ponds and with weather conditions. 

 If too much fertilizer is used in starting the pond it becomes so polluted 

 that all the midge eggs are killed. Two quarts of soybean meal per 

 100 cu. ft. of water will produce such conditions in a pond. It is better 

 to under-fertilize than to over-fertilize, because more may be added as 

 it is needed without over-polluting the water and killing the larvae. 



The length of time required to produce a culture of larvae varied with 

 the water temperature. Summer temperatures for the ponds experi- 

 mented with ranged from 20 to 28. 5 C. Usually 18 to 20 days were 

 sufficient for the culture to run, but when cool, cloudy weather conditions 

 prevailed for several days the period was extended 3 or 4 days. It is 

 probable that in a warmer climate the period could be reduced to 15 or 

 16 days. 



M. E. D. 



Bibliography 



Branch, Hazel E. 1923. The life history of Chironomus cristatus Fabr. with de- 

 scriptions of the species. J. N. Y. Ent. Soc. 31:15. 



CHIRONOMUS CRISTATUS* 



THE larvae grow readily in water charged with milk and no difficulty 

 has been experienced in obtaining heavy cultures and having them 

 thrive and maintain themselves in such a medium both indoors and out. 

 In the indoor experiments, white enameled pans of various sizes were 

 used. In these water was put to a depth of not less than % of an inch 

 and soil was added to cover the bottom. These pans were then stocked 

 with either egg masses or young midge larvae. Milk in a known pro- 

 portion to the volume of water in the pan was added to these pans daily; 

 thus the dilution for the best growing conditions was determined. The 

 water was not changed but sufficient fresh water was added each day to 



♦Abstracted from an article in /. N. Y. Ent. Soc. 31:15, 1923, by Hazel E. Branch, 

 University of Wichita. 



