the mouth parts are adapted for piercing and sucking and in which 

 the parasitic role may become of importance. One of the less 

 significant forms is the stable fly, Stomoxys calcitrans, the resem- 

 blance of which to the housefly is responsible for the commonly 

 held but erroneous notion that the latter is a biting type. Stomoxys 

 has also been suspected of being the transmitting organism of 

 certain important diseases, anthrax and infantile paralysis. One 

 of the forms now definitely known to be of the greatest significance 

 in the transmission of disease is the African tsetse fly, Glossina, of 

 the various species of which distributed throughout Africa, two, 

 G. palpalis and G. morsitans, are the carriers of the trypanosome 

 parasite of sleeping sickness. 



Other flies are significant because parasitic in the larval or 

 "maggot" stage. These flies, typified by the European flesh-fly, 

 Wohlfahrtia magnified, a related Canadian species, W. vigil, and 

 the American screw-worm fly, Chrysomyia macellaria, and indirectly 

 by various infestations, including skin nodules or "warbles" in 

 lower animals, may be said to conform to the usual habitus of egg 

 or larval deposition and development in decomposing flesh, with 

 the modification that living sites are occupied. These are repre- 

 sented by portions of the skin surface, open wounds, discharging 

 nasal or auditory surfaces, or even the interior of the digestive tube. 

 The condition is known as myiasis, and further as cutaneous, 

 nasal, or intestinal according to the particular type of localization. 



The mosquitoes, Culicidae, include a large number of dipterous 

 insects in which the mouth parts are somewhat differently modified 

 to form a piercing and sucking tube. They live upon plant juices 

 or animal blood; some, such as the species of common mosquitoes, 

 Culex, being for the most part significant as temporary parasites, 

 and others, such as the malarial mosquitoes (Anopheles) and the 

 yellow fever mosquitoes (Stegomyia), important as the carriers of 

 lower parasitic organisms. The life history includes aquatic 

 phases, the eggs, larvae or "wigglers" and the pupae being found in 

 water, a point of importance in controlling the spread of diseases in 

 which they play an accessory part. 



The Hemiptera include, in addition to a variety of aquatic and 

 leaf-inhabiting forms, the common bed-bug, Cimex lectularius. In 

 this form the body is dorsoventrally flattened, the anterior wings 

 reduced to small dimensions, while posterior wings are absent. 

 The species is chiefly remarkable for its nocturnal habits, living 

 in out-of-the-way places, such as the crevices in bed-frames, and 

 attacking human beings at night. The eggs are deposited in 

 similarly concealed situations. The hemipterous type is consid- 

 ered to be that to which the term "bug" is to be specially applied. 



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