14 



BULLETIN 329, U. S. DEPARTMENT OP AGRICULTURE. 



The head (PI. Ill, fig. 7) is light brownish-yellow in color, heavily marked 

 with brown on the lateral margins. The dorsal markings of the head are ar- 

 ranged in the form of a long central irregular blotch, with 

 two adjacent blotches extending diago- 

 nally on either side. 



The mandibles are similar to those of 

 8. venustum (fig. 12), but darker in color. 

 The raaxillse are infuscate and very hairy ; 

 the proximal portion of the maxillary 

 palpus is dark brown, with a few sparse 

 hairs ; the distal end transparent, bearing 

 a few conical processes. 



The rectal gills (PI. IV, fig. 7) are 

 simple, three branched, somewhat pointed 

 toward the distal end, and are curved 

 backward cephalically when extended. 



The caudal sucker bears from 60 to 70 

 rows of spines or hooks (fig. 6). 



The larvae were taken by the writer from several 

 streams in the vicinity of Spartanburg, S. C, from 

 June to October, 1913. They were separated from 

 the larvae of other species by the number of the 

 branches of the pupal filaments (formed under- 

 neath the larval skin) and determined from adults reared from 

 them and compared with the type. 



4 



I 

 'i 



Pig. 6. — Simulium 

 bract eatum . 

 Row of spines 

 from caudal 

 sucker of larva. 

 Greatly en- 

 larged. (Orig- 

 inal.) 



Fig. 7. — Simulium 

 j e n n ing si . 

 Antenna of 

 larva. Greatly 

 enlarged. (Orig- 

 inal.) 



DESCRIPTION OF THE LARVA OF SIMULIUM JENNINGSI. 



The larva of Simulium jenningsi is much smaller than 

 that of S. venustum and measures from 3.5 to 4.5 mm. in 

 length. The general color is light brownish yellow. The 

 head is of a uniform yellow with dark-brown blotches of 

 characteristic arrangement on its dorsal surface (PI. IV, 

 fig. 3), thus differing from venustum (PI. IV, fig. 4), which 

 usually has the pigment in these cells lacking. The an- 

 tennae (fig. 7) are slender and 4-segmented, the last seg- 

 ment being a short conical process; the first three seg- 

 ments are subequal in this 

 species, while the antennae 

 of venustum (fig. 8) have 

 the second segment longer 

 than the first. The labial 

 plate (fig. 9) is broader 

 than that of venustum 

 (fig. 5) the teeth more 

 even and equal in size, the 

 middle tooth not very 

 prominent, and there are 

 apparently only two large 

 and one small bristle along 

 each margin, while venustum has four to five large bristles on each side. 

 The mandibles are of the usual type, but rather weak and the teeth some- 

 what pale. 



Fig. 8. — Simulium 

 venustum. An- 

 tenna of larva. 

 Greatly en- 

 larged. (Orig- 

 inal.) 



Fig. 9. — Simulium jenningsi. La- 

 bial plate of larva. Greatly en- 

 larged. (Original.) 



