348 MEDICAL ENTOMOLOGY 



rooms containing exposed food, Howard counted 22,808 specimens of 

 Musca domestica, or ninety-eight per cent of the total number. Of the 

 remainder there are or were eighty-one specimens of Homolomyia canicn- 

 laris; thirty-seven of Muscina stabtilans; thirty-three of Phora femo- 

 ra ta ; eighteen of Lncilia caesar; fifteen of Drosophihi ampelophila; 

 ten of Sarcophaga trivia Us and seven of Calliphora erythrocephala. 



GROUP 2. NON-BITING, BLOOD-SUCKING SPECIES OF MUSCA 



The species of Musca which belong to this group arc blood-sucking by 

 habit ; they feed on the blood and serum which exudes from the bites 

 inflicted by such flies as Philaematomyia, Stomoxys, Bdellolarynx, Lyper- 

 osia, and the Tabanidae; or on serum which exudes from sores on the 

 skins of animals. It must, however, be clearly understood that these 

 muscids are not themselves capable of piercing the skin of an animal, for 

 their prestomal teeth are not sufficiently developed to enable them to 

 do so. 



They may often be seen in large numbers, worrying a biting fly in 

 a very characteristic manner. The)- push their proboscides down beside 

 that of the biting fly and cause it to withdraw its proboscis ; if they suc- 

 ceed they immediately suck up the drop of blood which exudes. The male 

 has the same habit as the female, and both can be observed flitting about 

 from spot to spot and from one animal to another, never remaining long 

 in one place. 



It is interesting to note that these species of Musca appear to 

 be common in the Philippine Islands. Mitzmain, in his paper on the 

 Bionomics of Stomoxys calcitrans, evidently refers to them when he 

 says, ' A peculiar feeding relation has been observed to exist between 

 ' Stomoxys and certain non-biting flies. I was curious to learn why 

 ' such large numbers of non-biting flies were generally found in collecting 

 ' insects from domesticated animals. When these were dissected and 

 ' examined microscopically, mammalian blood was found to be the 

 ' principal food constituent. My attention was attracted to the peculiar 

 ' grouping of the ectoparasites; groups of from two to five predominated. 

 ' On closer inspection the group was found to consist almost invariably 

 1 of more than one species, a Stomoxys usually being the central figure. 

 ' Where a Stomoxys was lacking, it was found that the group fed from 

 ' a common area with the heads of the individuals in close contact. 

 ' The food of these flies was found to be a droplet of freshly exuded 

 ' blood, and among the blood imbibers often not an individual belonged 

 ' to a species with a piercing mouth ; they consisted principally of house 



