— 7i — 



MOUTH-PARTS OF THE HOUSE-FLY. 



(Musca domestical 



In the house-fly, we find only the maxillary palpi and the 

 proboscis-like labium, with well developed labella. The 

 maxillary palpi are prominent, but are only one-segmented. 

 The labial trunk or proboscis may be described as being 

 made up of three portions, a basal third, the basiproboscis, 

 from which arise the maxillary palpi, and in which are im- 

 bedded two slender chitinous rods, the " maxillary tendons,'''' 

 probably representing the greatly reduced maxillae ; a mid- 

 dle third, the mediproboscis, strongly chitinized ; and a distal 

 third, the distiproboscis, including the disk-like, metamor- 

 phosed, fleshy, labial palpi, the labella. The labella is like 

 that of the horse-fly, but in the house-fly it is the only organ 

 for obtaining food. With it, traversed as it is by transverse, 

 horny, chitinous ridges, the " pseudotrachece " hard food 

 substances may be rasped so that fine particles of food mixed 

 with, or sometimes dissolved in, a salivary secretion, which 

 issues from the ridges, can flow into the mouth, along the 

 dorsal furrow oi the labial proboscis. 



Make a drawing of the m*uth-parts from a lateral view ; 

 and also of a portion of the labella, highly magnified, to 

 show disposition of the pseudotrachese. 



THE MOUTH-PARTS OF THE HONEY BEE. 



{Apis mellifica.) 



Most of the bees in alcohol, from among which the stu- 

 dent selects a specimen, will be found to have certain of the 

 mouth-parts protruding. These parts are the maxillae and 

 labium, united at base and associated to form a proboscis. 

 Before the detailed examination of these parts is begun, the 

 student should discover the labrum and mandibles. 



