i8 



ELEMENTARY ENTOMOLOGY 



Diptera. The flies have several types of mouth-parts, all essen- 

 tially suctorial. Those of the horse-fly and mosquito are good 

 examples of the piercing type (Figs. 15, 18, 20). Superficially they 

 resemble those of the Hemiptera, but the sheath of the beak is not 

 so strong and is quite open above, and there are six lancetlike or- 

 gans which in the horse-fly 

 are quite strongly devel- 

 oped. The esophagus is 

 controlled by sets of mus- 

 cles which make it an effec- 

 tive bulb for pumping up 

 the food. The common 

 house-flies and blow-flies 

 have mouth-parts (Fig. 19) 

 adapted for rasping or lap- 

 ping rather than for pierc- 

 ing, though the liquid food 

 is sucked up in much the 

 same way. The proboscis 

 consists principally of the 

 very complex labium, or 

 lower lip, which is very 

 much expanded at the tip 

 to form a pair of fleshy 

 lobes. When looked at 

 under the microscope, the 

 tip of the proboscis is 

 seen to contain a series 



FIG. 20. Mouth-parts of horse-fly (Tabamis] 



Upper figure showing mouth-parts separated, and 



lower figure showing lancets dissected out. (After 



J. B. Smith) 



of grooves and transverse 

 horny ridges with sharp, 

 projecting edges. With 

 these rasplike projections the fly is enabled to scrape the surface 

 of the food and gradually loosen small particles, which are dissolved 

 or carried in the saliva to the mouth. 



Hymenoptera. The mouth-parts of the Hymenoptera include 

 both biting and sucking types. The saw-flies and ants (Fig. 22) 

 have well-developed biting mouth-parts, which are used as such, 

 while in the wasps and bees the maxillae and labium form a tube 



