58 



Genus 

 STOMOXYS, Geoffroy. 



Stomoxys calcitrans, Linn. 

 Plate 29. 



The similarit}- in size between this species and the House-fly 

 {Mtisca domestica, Linn.) sometimes causes Stomoxj's to be mistaken 

 for the latter, with the result that the House-fly is occasionally 

 supposed to be capable of biting. Apart from points of difference 

 afforded b)- markings, however, Stomoxys, not to mention other struc- 

 tural differences, can always be recognised b}- the little black, rigid 

 piercing proboscis, which, as shown in the plate, when not in use 

 projects horizontally in front of the head, whereas the fleshy, non- 

 biting proboscis of the House-fly is normally carried drawn up into 

 a cavity on the under side. The sexes of the present species can be 

 distinguished by the front (space between the eyes) in the male 

 being scarcely more than half the width of that in the female. 



Stoinoxfs calcitrans, which is the only European species of its 

 genus, and, like H(.ematobia stiinu/<ins, Mg. (Plate ^o, Fig. i;, plagues 

 both men and cattle, is common and generally distributed in the 

 British Islands in summer and early autumn, and especially abundant 

 in England in August and September, when it ma)- often be seen 

 sitting about in numbers on rails and gates in i^asture-fields. The 

 Museum series contains specimens from many different localities 

 between and including the Southern Sutor, Cromarty, N.B., and South 

 Devon. The dates of capture range from May 27th (Folkestone 

 Kent) to October 3rd (Staines, Middlesex). 



With reference to this and the following species {Hamatobia 

 sthnulaus, Mg.), Colonel Yerbury writes : — " These are common 

 species in the Thames Valley ; 5. calcitrans was abundant, too, at 

 Newmarket in October, 1905. The amount of pain produced by 

 the bite of a Dipteron probably depends upon the idiosj^ncrasy of 

 the person bitten ; to the writer, however, the bite of these two 



