100 INSECUTOR INSClTliE MENSTRUUS 



Type from Great Falls. Virginia, October 21 (Nathan 

 Banks) ; paratype from Falls Church, Virginia, June 7 

 (Banks). 



This is similar to A. dilatata Brues. 



Together with the four preceding species it has the anterior 

 tarsi enlarged. All the members of this group known from 

 North America may be distinguished by the aid of the follow- 

 ing key : 



1. Scutellum with four equally strong bristles 2 



Scutellum with only two bristles 5 



2. First division of costa noticeably longer than the second ; 



costal fringe of moderate length 3 



First division of costa about equal to the second ; costal 

 fringe very short magnipalpis Aid. 



3. Halteres pale yellow ; palpi of male much enlarged and with 



only minute bristles projccta Becker 



Halteres brown or black ; palpi bristly as usual 4 



4. Costa two-fifths the wing length ; hypopygium with very 



large bristles scopalis Brues 



Costa extending to the middle of the wing; hypopygium not 



noticeably bristly californiensis Malloch 



.5. Halteres black ; costal cilia short 7 



Halteres pale 6 



6 Costal cilia very long pulla Brues 



Costal cilia short johnsoni Brues 



7. Mesopleural bristles of approximately equal size palpata Brues 



One mesopleural bristle enlarged, much longer and stouter 



than the remainder 8 



8. Posterior tibiae with well-developed setulse, front as high 



as broad capillaris Brues 



Posterior tibise (without distinct setulse; front one-fourth 

 broader than high dilatata Brues 



Aphiochaeta centralis, new species. 



Female. Length 3.3 mm. Black, the pleurae and legs very 

 dark brown ; front legs distinctly lighter ; antennae brown- 

 black ; palpi dark yellow, much infuscated above; wings with 

 a brownish cast, more pronounced apically ; halteres black. 

 Front about one-third broader than high, with large bristles ; 

 four ])roclinate bristles, the lower pair half the size of the 

 upper and close to them although more approximate; upper 



I 



