426 Annals Entomological Society of America,  [Vol. V, 
angular, and highly chitinized point. At intervals along the 
inner surface, are sense organs, each with a short clear hair. 
The Hypopharynx is as long as the labrum, and consists, 
until its distal end is neared, of a tube. (Fig. 3, hp.,) The apical 
part, however, is flattened and membranous, and quite unsuited 
for piercing. 
Method of Feeding. 
When about to feed Stomoxys calcitrans raises the body 
somewhat higher than the normal position on the legs, and 
brings the proboscis into practically a vertical position. The 
posterior part of the body is, in some cases, decidedly elevated. 
The tip of the proboscis is in this manner brought into contact 
with the skin of the host and the first puncture made. This, I 
believe, is performed by the labella, which are slightly parted 
so that the chitinous teeth and blades can be brought into 
operation. If blood emerges from the puncture it is sucked up, 
but if not I imagine the labella are depressed laterally and the 
point of the labrum forced into the host. I have observed on 
several occasions, when allowing S. calcitrans to bite, that 
there is often a decided stab after the first puncture had been 
completed. 
The saliva is conducted to the wound by means of the 
hypopharynx, into the base of which the salivary duct opens. 
(Sd. int Figs. 2.and “4"sG) imme) 
The blood is conveyed to the pharynx by means of the tube 
formed by the labrum and hypopharynx combined, which is in 
turn enclosed by the dorsal groove of the labium. 
The pharynx proper has strongly chitinised walls, and pow- 
erful muscles, which make it well adapted for sucking. 
Digestive System. 
The relative position of the different parts of the alimentary 
canal in Stomoxys calcitrans are shown, in diagrammatic form, 
in Fig. 2. Beginning with the proboscis it will be seen to con- 
sist of the following parts: J. hp., the canal formed by the 
labrum and hypopharynx combined. g., the tube leading from 
this canal to the pharynx proper. ph., the pharynx proper. 
oe., the oesophagus, which passes through the brain at the 
point indicated. pr., the proventriculus, from which two ducts 
pass backward, viz., d. ss., the duct of the sucking stomach, 
