SIMULIUM. 35 



Simulium mexicanum Bellnrdi. 



Female. — Black, siibopaqiie, only the apical four abdominal seg- 

 ments distinctly shining. Frons and face ■\vhite-dusted; antenna; 

 brown, with basal two joints and base of third joint yellowish; palpi 

 brown. Prescutum yellowish, iileura) with sutures and posterior 

 portions yellowish; scutellum brownish yellow; postscutum brown, 

 whitish pollinose; scutum unstriped and weakly white-dusted. 

 Abdomen with basal scale opaque black; first segment below scale 

 yellow or brown at base, opaque black at apex; segments 2— t gray- 

 ish pollinose, with opaque black fascia?, which are broadest at middle 

 and taper on each side; apical four segments glossy black; venter 

 brownish yellow. Legs black, 3'ellow as follows : Coxse, femora, and 

 bases of tibiae of fore pair; apices of coxa?, trochanters, bases and 

 apices of femora, basal halves of tibia?, and basal halves of first and 

 second joints of tarsi of mid and hind pairs; base of third joint of 

 mid tarsi. AVings grayish, thick veins brown. Ilalteres yellow, dark- 

 ened at base of stalk. 



Frons almost parallel-sided, not one-third as wide at vertex as 

 the breadth of head, surface hairs black; face longer than frons and 

 wider than frons at upper margin, one-third longer than wide, sur- 

 face hairs black; hairs on palpi brown; postocular cilia black. Scu- 

 tum with brassy yellow, scalelike pilosity, w^hich is arranged in irregu- 

 lar groups on the disk ; besides the pilosity there is on the disk short, 

 closely placed, black, upright hairs, which are most distinct on the 

 margins; pleural tuft black or brown; postspiracular area pale- 

 haired; scutellum with yellow^ pilosity and longer, upright black 

 hairs. Basal fringe of abdomen yellow, apical four segments with 

 short black hairs, which are longer at extreme apex. Legs with 

 close-lying yellow pilosity and long, upright, black dorsal hairs, 

 which are very noticeable on the apices of the tarsal joints; fore tarsi 

 with the normal paired apical hairs on joints 1 and 3; the legs are 

 strong and the fore tarsi very distinctly thickened or compressed 

 laterally; tarsal claws with subbasal tooth (PI. II, fig. 6). 



Length, 4 mm. 



Two females, Cordoba, Mexico, January 30, 1908 (F. Knab). 



These specimens agree so closely with the description given by 

 Bellardi ^ that I have no hesitation in associating them with his 

 species. The early stages are unknown. 



A translation of Bellardi's description of the male of Simulium 

 ■mexicanum is as follows: 



Black. Head black, frons prominent, trianpnlar. with whitish reflection : 

 antennae black, first joint and base of second [second and base of third ?] yel- 

 low ; face prominent, black, the epistome yellowish, with grayish reflection : pnljii 



» Saggio di Dltterologla Messicanu, App. G, 1862. 



