PREDACEOUS INSECT ENEMIES 171 



observations of a number of persons (Hi t he destruction of M. domes- 

 tica by ants. Capt. P. L. Jones found it impossible to rear M. 

 doniestica in the Philippine Islands unless the eggs and larvae (in 

 manure) were protected from ants. Stallman (1912) reports the 

 destruction of fly larvae by red ants in Arizona, It would appear, 

 however, that usually ants do not prey upon ilf. doniestica to an 

 extent sufficient to make the results of their predatory habits 

 appreciable. 



The common species of wasps (Vespa spp.) have been frequently 

 observed by myself and others preying upon flies which they 

 occasionally destroy in large numbers. A Canadian engineer, who 

 had been engaged in railroad construction in northern Ontario, 

 described to me the mystification caused by the presence of 

 large numbers of the wings of flies on the table of their cabin. 

 On investigation, it was found that a large species of Avasp was 

 catching the flies in the cabin ; after capturing a fly the wasp took 

 it to a beam immediately over the table and there cut off the 

 wings before eating it or carrying it away. 



The large hairy Robber-flies of the dipterous family Asilidae 

 frequently catch flies. I have observed and captured Laphria 

 canis Will, in the act of catching and eating M. domestical. 



In some parts of India it is the custom, I have been informed 

 by residents in that country, to employ a species of Mantis, one of 

 the predatory " praying insects," to destroy the house-flies. 



Compere (1912) has found earwigs destroying the maggots of 

 stable-flies in fresh manure in southern China and believes that 

 they are an important factor in the control of house-flies in 

 Hongkong. It is hardly likely, however, that they would exert 

 so great an influence as is suggested. 



The destruction of the larvae of M. doniestica by the larvae of 

 the allied muscid Muscina stabidans and of Hydrotaea dentipes, 

 is recorded by Portchinsky (1913). He found that the larvae of 

 M. stabulans, having completed the second stage, follow and attack 

 the larvae of M. doniestica and soon exterminate all that happen to 

 be living with them. The larva of M. stabidans that had killed 



^ Since the above was written I have described (Hewitt, 1914) the predaceous 

 habits of the common yellow dung fly Scatophaga stercoraria L. which was found 

 destroying M. doniestica and other Muscidae. 



