76 ILLINOIS BIOLOGICAL MONOGRAPHS [394 



15(14) Segments with five or six annulets, annulets 2 and 4 setiferous; antennae usually not 

 with all segments fused together; larvapods usually with many more than two 

 setae as viewed from lateral aspect; setae on body not very long; glandubae usually 

 conspicuous and stalked 16. 



16(17) Segments with six annulets; larvapods with 7-10 setae as viewed from lateral aspect; 



surpedal areas at least in part always marked with gray; latus of abdomen never 



with numerous brownish spots; tenth abdominal tergum sometimes distinctly 



pointed and produced caudad and with many conspicuous glandubae near the caudal 



margin; larvae usually feeding on monocotyledonous plants. . .Pachynematus Konow. 



17(16) Segments with five annulets; larvapods with 3-5 setae as viewed from lateral aspect; 

 surpedal areas not marked with gray; latus of abdomen sometimes with numerous 

 brownish spots; tenth abdominal tergum never distinctly pointed and produced 

 caudad; larvae usually feeding upon willow ^«/aMroMewo/«^ Konow (in part). 



18(1) Tenth abdominal tergum with a pair of caudal protuberances 19. 



19(20) Gall-makers and leaf-rollers; segments with four annulets; annulets 1, 2, and 3 

 setiferous; antenae flattened; body setae more than twice as long as spiracles; 

 caudal protuberances normal in form and position or loidimentary or borne on a 

 small caudo-mesal projection, if normal in form and position, the tergum with 

 paired colored markings Pontania Costa (in part) . 



20(19) Free leaf-feeders; segments usually with five or sLx annulets, if four, annulets 2 and 4 

 usually setiferous; antennae conical or flattened 21. 



21(22) Antennae conical, segment 2 complete, segment 3 ring-like, its cephalic portion 

 subequal in length to caudal portion; body on latus with eleven conspicuous blackish- 

 brown spots, surpedal and subspiracular areas of abdominal segments 1-9 and venter 

 between larvapods of abdominal segments 2-8 similarly marked; spiracles not winged; 

 caudal protuberances of ultimate segment small, blunt, not longer than wide at 

 proximal end; segments with five or four annulets, with annulets 2 and 3 or 2 and 4 

 setiferous Croesus Leach. 



22 (2 1 ) Antennae conical or flattened ; if conical, segment 3 not ring-like but reduced in length 

 on cephalic aspect; body not marked as in Croesus; spiracles winged or not winged; 

 caudal protuberances of ultimate segments not blunt, minute, but usually much 

 longer than wide at proximal end 23. 



23(24) Segments apparently with five annulets; annulets 2 and 3 setiferous; antennae 

 flattened, with segment 3 complete; body-setae subequal in length to spiracles; smaller 

 larvae, length, 13-15 mm Amauroncmatus Konow (in part). 



24(23) Segments with four or six annulets; annulets 2 and 4, rarely 1, 2, and 3, setiferous; 

 antennae conical or flattened, segment 3 complete or incomplete; body-setae often 

 longer than the length of abdominal spiracles; small to moderately large larvae, 

 length, 15-23 mm Pteronidea Rohwer (in part). 



DiPHADNUS HARTIG 



Larvae small, greenish; length less than 14 mm.; body cylindrical, in- 

 creasing in size to abdominal segments 5-6, tapering at each end; thorax not 

 swollen; tenth abdominal tergum without a pair of caudal protuberances; 

 third abdominal segment with six annulets, annulets 2 and 4 setiferous; 

 spiracles distinctly and usually equally winged; head marked with black or 

 brown streaks along epicranial stem and dorsad of ocellarae; somewhat 

 compressed cephalo-caudad; labrum with median emargination broad and 

 deep and with median longitudinal depression; antennae distinctly conical, 



