ENTOMOLOGIST AND BOTANIST. 



229 



ON THE TRANSFORMATIONS OP SIMULIUM. 



lACKEJJ, NEW YCUK. 



Explanation of Figure 145— (a) Larva from a side view, 

 enlarged, the hair-line above showing natural size; (6) 

 same, from a back view; (c) pupa, venti-al view, enlarged; 

 (rf) same, dorsal view; (c)pupal pouch, enlarged, the hair- 

 line showing natural size- — After Verdat. 



Several excellent observers have studied the 

 natural history of this genus, wMch, except in a 

 U'w doubtful points, may be considered as fairly 

 fhiiidated. The following account has been 

 prepared by comparing- my own obsei-vations, 

 made upon a species which I found in the envi- 

 rons of Wasliington, with those of Verdart and 

 others. In this account, the discrepancies be- 

 tween authors have been carefully noted, in 

 order to draw the attention of future observers 

 to those points which deserve to be investigated. 

 It must be borne in mind, however, that some 

 of these discrepancies may be due to the fact that 

 the observed larvse belonged to diflferent sjiecies 

 of the genus Simulium. 



Tlie lai-vse are frequenth' found in small streams 

 of running water, in large societies, fastened by 

 their tails to stones or to the leaves or stalks of 



water plants. They are about 0.35 of an inch 

 long, subcylindrical, attenuated in the middle, 

 incrassated towards both ends ; the latter third 

 of the body is stouter than the anterior third, 

 and almost club-shaped ; head subquadrate, yel- 

 lowish, with a pair of small, approximate black 

 dots on each side. Verdat took them for eyes, but 

 I did not discover the slightest convexity in them. 

 They are evidently below the horny shell of the 

 head. Antennse slender, subulifnnn. ;iiJij;uciitIy 

 four-jointed. Epistoma horny. s\ili(iiaiii;ular; 

 upperlipfleshy, fringed with long, del irate liairs; 

 its ordinary position is not horizontal, but almost 

 vertii'al, at riglit angles ^\'ith the upper surface 

 of the head and as if lapping over the orifice of 

 the lesophagus; (it can be perceived only by 

 looking in the direction of the axis of the body, 

 as it is concealed between the other parts of the 

 mouth) ; between the mandible and the c']iist(>ina 

 and close by the antennie the remarkable tlalx'lli- 

 form organs, peculiar to tliis larva, are situated ; 

 they consist of a stout stem bearing a fan of 

 thirty-five or forty delicate homy rays, each of 

 the shape of a very long, slender scythe; they 

 open and close like a fan ; when closed, tlie tip 

 of this fan is inside of the mouth and touches the 

 tip of the mandibles ; its opposite end forms an 



Explanation of Figure 146 —(o) Head of larva, from iin- 

 diiside; (6) its mandible; (c) maxilla; (c) under lip; if) 

 upper li|)— all enlarged; (d) larva natm-al size, attaclied 

 t'l a ijhmt; to) pupa natural size, within its pouch— j4/tcr 

 Verdat. 



angle or knee with the stem. They may be 

 compared to the antennas of the 3Ielolonthidw, 

 only the rays are much more numerous. The 

 mandibles consist of a pale-colored, apparently 

 fleshy, basal piece, with a tuft of hairs on the 

 inside, and to their upper extremity are fastened, 

 1st, a small, horny, black tooth, having the shape 

 of an ordinan- mandible, bifid at the tip. and 

 with a very minute projection inside of this in- 

 dentation; 2d, a brush of hairs, or perhaps of 

 scythe-shaped organs analogous to tliose form- 

 ing the fan. The maxillm consist of a stout, 

 fleshy basal piece, an elongated apparently two- 

 jointed palpus (first joint cylindrical, second 

 short, rudimentary), and an internal, i-ounded, 

 thumb-shaped lobe, bearing tufts of haii-s on both 



