I 4 MEDICAL ENTOMOLOGY 



c. The opening of the salivary ducts, emptying into the 

 oesophagus, and the pair of salivary glands. 



d. The crop, or short food-receiving chamber, emptying into 

 the stomach proper, a longer cylindrical chamber, anterior to 

 which are the gastric caeca, and posterior the hair-like malphigian 

 tubules. 



e. The intestine, a long, slender, coiled tube posterior to 

 the stomach, consisting of three parts, the ileum, colon and 

 rectum, the latter a short straight tube ending in the anus. 



B. If time remains the student is urged to study the internal 

 anatomy of a stablefly for purposes of comparison. 



a. Note the connection between the blood-sucking proboscis 

 and the oesophagus. x 



b. How does the crop compare with the crop of the grass- 

 hopper? Note its adaptation to the storage of blood. 



EXERCISE 6 



COMPARATIVE STUDY OF THE BITING AND SUCKING LICE 



Use for this exercise slide mounts in balsam of Hamatopinus 

 piliferus, the sucking louse of the dog, and either Trichodectes 

 lotus, the biting louse of the dog, or Trichodectes scalaris, the 

 biting louse of cattle. 



The biting lice belong to the order Mallophaga, while the 

 sucking lice belong to the Order Hemiptera, Family Pediculidae. 

 These two groups of parasites are not always easily distinguish- 

 able without the use of a compound microscope. The bodies of 

 both are flattened dorso-ventrally, and in both wings are absent. 



With a mounted specimen of each in hand, examine them 

 under a compound microscope (low power) and determine the 

 following characters, drawing each specimen. Your drawings 

 should be large enough to cover at least half a page of ordinary 

 notebook size. 



