242 NORTH AMERICAN DIPTERA 



Family Platypezidse — The Flat-footed Flies 



Platypeza species. 



Tliese are small flies with short hair and bristles, characterized by 

 the wing" venation and peculiarly shaped posterior tarsi, the basal seg- 

 ment being (usually) much flattened and sometimes strikingly orna- 

 mented. 



Head hemispherical, as l)road or broader than the thorax and 

 closely applied to it; face depressed, short and broad; eyes bare, holoptic 

 in the males and in some females; ocelli present. Antennae porrect, 

 the basal two segments short, the third more or less elongate-oval, pyri- 

 form or conical, with a terminal arista. Thorax rather stout, the 

 mesonotum and scutellum with bristles. Legs short and strong, the 

 posterior pair more or less thickened and at least the basal segment of 

 their tarsi thickened or variously ornamented. Wings rather large; 

 third vein simple, tlie fourth sometimes forked; apical cell open; basal 

 cells rather small; ])osterior crossvein rarely absent. Abdomen rather 

 short, broad and tapering or laterally compressed; hypopygium gen- 

 erally small. 



The larva? have been found in fungi and are flat, oval in outline, 

 with jointed thread-like appendages on the sides of the segments. The 

 puparia are rather similar to tlie larva? in appearance. 



For the most part the Platypczids are not common in collections 

 nor are they often met with in the field. Williston states that they 

 have been observed dancing in small swarms but they are usually found 

 ujion the leaves of bushes and low trees where they move about in a 

 characteristic, jerky but remarkably agile manner. Mr. Johnson has 

 obtained most of his specimens of Af/athovijiia by sweeping foliage. 

 The species of Calliniyia prefer moist woods. Fewer than thirty North 

 American species are known. 



