ORDER DIPTERA : THE PUPIPARA 185 



They are distinguished by the tough or strongly chitinised 

 integument ; by the head, which, as a rule, is either broadly 

 impacted against, or turned right back on the thorax ; by the 

 broad thoracic sterna; by the often — though not always — 

 indistinctly segmented abdomen; by the reduction of the 

 antennae; and by the stout legs — sometimes with the ist 

 tarsal segment elongate — ending in remarkably strong grasp- 

 ing claws, the heel of which is almost as sharp as the tip. 

 The proboscis, which is retractile, is otherwise not unlike that 

 of Glossina. Wings are sometimes present, sometimes 

 vestigial, sometimes caducous, and sometimes altogether 

 absent ; when present their veins may be complete, or may 

 be incomplete and a good deal crowded together in the 

 antero-internal part of the wing. Though the Pupipara are 

 blood-suckers they do not, except fortuitously, attack man. 

 The following families are included in this group : — 

 (i) HippoboscidcB (Fig. 72). Head commonly flattened 

 and broadly impacted against the thorax ; legs strong but 

 usually not remarkably elongate ; wings well formed, or 

 rudimentary, or absent; abdomen unsegmented. Parasitic 

 on mammals and birds. 



(2) Streblidce. Head with a freely movable neck. Legs 

 long, with the 5th tarsal segment usually enlarged. Wings 

 present or absent. Abdomen imperfectly segmented. Para- 

 sitic on bats. 



(3) Nycteribiida (Fig. 73). Long-legged, wingless, spider- 

 like flies, with the head turned right back so as to repose 

 upon the thorax, and with the ist tarsal segment of the 

 legs greatly elongate. Abdomen segmented. Parasitic on 

 bats. 



(4) Braulidce. Consisting of a minute wingless parasite 

 of bees. 



In addition a small, unsegmented, headless insect, known 

 as /Lscodipteron, which was found buried in the skin of a bat 

 in the Dutch East Indies, has been included among the 

 Pupipara, as the type of a family Ascodipteridce. 



Family HlPPOBOSClD^ (iTnro? = horse ; /3o(ncer(/ = to feed). 

 The only family that need be further considered is that 

 of the Hippoboscidce (Fig. 72). In the HippoboscidcB, or 

 tick-flies, the head is sometimes globose and freely movable, 



