CHAPTER XI 

 Muscidse (continued): The Blood-sucking Muscidse 



2. Blood-sucking Muscidce. 



In the majority of the blood-sucking Muscidce the pro- 

 boscis (Figs. 58, 60, 65) is strongly chitinised and rigid, is little 

 or not at all retractile, and is more or less slender and taper- 

 ing, and the labella are small, stiffly chitinised, and serrated 

 or spinose (Fig. 57), so that the proboscis forms a very efficient 

 augur for piercing epidermis. Occasionally, however, the 

 proboscis is only partly chitinous and is fully retractile, and 

 the labella are large and fleshy, but even in this case strong 

 teeth capable of cutting through skin are present. In other 

 respects the proboscis resembles that of other Muscidse, being 



Fig. 57.— Labella of 5iomox2/s. 



longitudinally grooved on its dorsal surface so as to ensheathe 

 the epipharynx and hypopharynx, which together form a 

 tube by apposition and basal interlocking. As in other 

 Muscidse, mandibles and maxillae are absent. The blood- 

 sucking habit is not confined to the female, but characterises 

 both sexes equally. 



As regards their connection with disease ; as, with the 

 glaring exception of Glossina and perhaps of Stomoxys, none 

 of them habitually attacks man, they are not — Glossina\i€\v\g, 

 of course, the notorious exception — likely to be the ordinary 

 and necessary agents of any human infection, though of 

 course they must all be regarded with suspicion as fortuitous 

 or at least potential " carriers." In the case of domestic 



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