june, '16] evans: breeding habits of common house-fly 361 



Summary 



1. With one exception house-flies have not been found breeding in 

 garbage. In this case the garbage was neutral. Their presence about 

 garbage cans is for feeding purposes. 



2. The eggs and larvae were able to develop in manure wet with am- 

 monia up to .7 per cent in a seeminglj^ regular manner. Above this 

 per cent their development is more or less inhibited. 



3. The development of eggs and larvae was found to be inhibited 

 in all strengths of hydrochloric acid. 



4. The pupae metamorphose regularly from both acid and alkali 

 which is prohibitory to the eggs and larvae. 



5. Spraying of manure containing eggs and larvae prevents to a 

 great extent their further development. When manure is sprayed 

 it prevents largely the deposition of eggs. 



6 House-fly larvae were not found living in the body of cow drop- 

 pings. They were found in small numbers in the layer of earth just 

 below the pile. 



7. The larvae were found to be sensitive to moisture in large quanti- 

 ties. W^hen a medium was too wet they were found to leave it in a 

 manner quite similar to their reaction in the case of acid. 



8. Manure stored in bins was found not to be a good place for the 

 breeding of flies due to the growth of mold which is usually found on top 

 and also to the wet condition of the manure deeper down. 



9. Hydrochloric acid was found to be an effective larvicide. 



In an interesting paper (5) which has appeared since the completion 

 of this work, M. E. Roubaud working in the military camps of the 

 French army found that he was able to destroy the larvae of the domes- 

 tic fly by merely turning the inner parts of the pile over the fresh 

 manure which contains larvae. He finds that the heat generated by the 

 manure as well as the gases which are formed during fermentation are 

 very fatal to the larvae when they are exposed to them. At 50 C. 

 the larvae are killed in three minutes; at 51 C. in one minute; at 59 C. 

 in five to seven seconds; and at 60 C. in from four to five seconds. He 

 has found that the middle of a manure pile may develop a heat of 

 from 70 to 90 C. He also finds that flies do not breed to any extent in 

 garbage. It seems justifiable to think that this developed heat may be 

 the cause of so few larvae in the center of the manure piles examined 

 during the course of the work, reported by the present writer; it may 

 also account for their not breeding well in manure bins. Roubaud 

 does not state why flies do not breed well in garbage. 



