INSECUTOR INSCITI^ MENSTRUUS 77 



A NEW SIMULIUM FROM TEXAS 



(Diptera, Simuliidce) 

 By FREDERICK KNAB 



Among the Diptera recently submitted by the Bureau of 

 Entomology for determination occurred the following un- 

 described species from the vicinity of Dallas, Texas. 



Simulium mediovittatum, new species. 



Female: Occiput, frons, and face densely whitish gray pol- 

 linose, with numerous fine but long silvery hairs ; frons broad, 

 above about one-third the width of the head, strongly nar- 

 rowed toward antennae. Antennae rather stout dull ferrugi- 

 nous, tinged with black beyond the second joint and with fine 

 appressed white pubescence. Scutum short, convex, blackish, 

 densely whitish gray pruinose, a median, rather broad, red- 

 dish brown stripe extending from anterior margin to posterior 

 fourth ; a pair of elongate whitish spots at anterior margin on 

 either side of median stripe, indistinct and only visible in some 

 lights; sublaterally a paler, indistinct brownish stripe, broad 

 and nearly straight; vestiture of rather abundant, small and 

 slender, evenly distributed, yellowish silvery hair-scales ; ante- 

 scutellar area triangularly produced into scutellum, strongly 

 impressed each side of middle. Scutellum narrow, compressed, 

 blackish, gray pruinose, concolorous with scutum, clothed with 

 long, yellowish silvery hairs. Postnotum black, gray pruinose. 

 Pleurae gray with silvery luster. Abdomen dorsally yellowish 

 gray marked with black; a median series of large, rounded, 

 deep black spots on segments 2-6, touching bases of segments 

 but pale margined at the sides and behind; laterally these 

 segments are blackish with broad apical pale margins; distal 

 segments gray ; venter gray. Front legs with the coxae brown- 

 ish yellow, the femora blackish, yellowish at base and apex, 

 tibiae dull yellowish basally and with a white reflection, shad- 

 ing to black beyond the middle; tarsi wholly black. Middle 

 legs with the femora dull ferruginous yellow; tibiae similarly 

 colored basally and with a whitish sheen, the distal half black- 



