June, '16] EVANS: BREEDING HABITS OF COMMON HOUSE-FLY 357 



manner except in bottles 5 and 6 where they wandered about a great 

 deal, appearing restless. From these observations it appears that the 

 highest amount of ammonia that the house-fly is able to breed in suc- 

 cessfully lies between .7 per cent and 1.4 per cent. 



An examination of the acid series showed that the eggs had hatched 

 in only bottles 1 and 2. Bottle 1 contained three larvae while bottle 

 2 contained but one. All of these larvae left the manure and crawled 

 about the sides of the bottles. None of the eggs had hatched in the 

 other bottles. 



Another series of experiments similar to those conducted on the 

 eggs was carried out using larvae instead. A number of the larvae 

 were placed in each bottle of the acid and alkaline series and were 

 found immediately to bury themselves in the moistened manure. 

 The next morning a number of the larvae in bottles 5 and 6 of the 

 alkaline series were found to be dead. The rest had left the manure 

 to crawl about the sides of the bottles. Later a single larva in bottle 

 6 pupated. The larvae in the other four bottles remained buried in the 

 manure and a few days later had pupated. These metamorphosed 

 into adults in a regular manner. The larvae remained buried in the 

 acid series for a short time, when they left the manure to crawl rest- 

 lessly about the bottles in which they were confined. Those in the 

 higher percentages of acid died on the second day; those in the lower 

 percentages lived for some time but eventually died. None were 

 found to have pupated in the acid series. 



Only three experiments were conducted with the pupae. A number 

 of pupae had been found to metamorphose regularly from alkali during 

 the course of the other experiments so it was not thought necessary to 

 test their resistance for more than the higher strengths. This was 

 also done for acid as well as distilled water. Large numbers of pupae 

 when placed in earth which had been moistened with distilled water, 

 .75 per cent acid or 2.1 per cent ammonia, were found to metamor- 

 phose seemingly without inhibition. This probably indicates that the 

 pupae are insensible to substances which may be larvicides. The 

 tough coat of the pupa undoubtedly serves as a good protection. 

 Earth was used in these experiments instead of manure as the larvae 

 are known to pupate in earth when possible. 



An attempt was made to get flies to breed in garbage by confining 

 them with it but in no case were they found ever to lay their eggs 

 when so confined. Manure which had been leached out was moistened 

 with the juice of garbage and a number of flies placed with it but all 

 -efforts to get them to breed in it failed. When larvae were placed 

 with such manure they left it soon and crawled about the containing 



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