128 



MORE MINOR HORRORS 



in the field. Later in the year, at the 

 beginning of autumn, they are frequently 

 found indoors, and in some ' fly counts ' they 

 have furnished quite 50 per cent, of the 

 flies of a country house, the remaining 50 per 

 cent, being made up of many other species and 



genera. When resting 

 on a vertical surface 

 Stomoxys generally has its 

 head pointing upwards, 

 whereas, as a rule, the 

 house-fly rests upside 

 down. The adult fly 

 feeds upon any decaying 

 matter; but whenever it 

 can, it sucks the blood of 

 vertebrates, and at times 

 is a real nuisance to 

 animals as well as human 

 beings. So voracious are 

 they that should a well- 

 fed one be injured, the others immediately 

 attack it and suck up every drop of blood 

 which it had secured for its own food. 



It has often been disputed whether a 

 meal of blood is essential to the female mosquito 

 before oviposition, but it seems perfectly clear 

 that the female Stomoxys can produce fer- 

 tilised eggs without having had a meal of 

 blood. 



Fig. 40. — Side view of 

 head of Stomoxys calcUrans. 

 A, Proboscis in resting posi- 

 tion ; B, proboscis extended. 

 (After Graham Smith.) 



