476 



NORTH AMERICAN DIPTERA 



Family Nycteribiidse 



Basilia species. 



Small, spider-like, wingless flies. 



Head oval, folding back when at rest in a groove on the dorsum of 

 the thorax. Antenna short, two segmented, the oval terminal segment 

 with bristles, inserted in cavity; eyes and ocelli vestigial. Thorax 

 depressed, laterally and anteriorly with comb-like bristles. Abdomen 

 oval, with more or less distinct segmentation. Legs long, the knees at 

 rest prominent above the thorax; femora broad; tibiae clubbed or shovel- 

 shaped; basal tarsal segment very long. Halteres pendunculate or 

 sessile, often indistinct. Larviparous. 



The members of this family are all parasitic upon bats and occur 

 throughout the tropics and subtropics but are most numerous in the 

 Old World. 



Ferris* considers that we have but one genus in North America and 

 perhaps two genera in the western hemisphere. Nycterihia possibly 

 occurs in Brazil but there are no positive records from other parts of 

 the continent. The two genera are separable as follows: 



1. Eyes absent Nycteribia Latreille 



Eyes present, two-facetted Basilia Ribeiro 



* 1924. Ent. News, xx.xv, pp. 191-199. 



