100 ILLINOIS BIOLOGICAL MONOGRAPHS [418 



The Hylotominae in the adult stage is closely allied to the Schizocerinae. 

 but in the larval stages their affinities, if extant, are not so manifest, 

 The laravae are peculiar in possessing six-segmented -thoracic legs and 

 varying numbers of larvapods. The shape and general appearance of the 

 larvae are so characteristic that they alone are sufficiently reliable for 

 identification in the field. Two genera are represented in the Nearctic 

 region, the genus Atomacera, which includes only a few species, has not 

 been studied. 



Hylotoma Latreille 



Head, conspicuously shiny black, brown or yellowish, or with a brown 

 median streak; body with minute blackish tuberculate setiferous spots 

 forming interrupted longitudinal rows along some or all of the subdor- 

 sal, latero-dorsal, supraspiracular, subspiracular, and pedal lines; annu- 

 lation usually 2, 3, 1; annulet 1 with a few minute setae, annulets 2 and 

 3 with a transverse row of a few stiff brown setae together with very 

 minute setae scattered around the larger setae; subspiracular tubercles 

 obsolete; pedal area prominent, produced laterad and oblique, extending 

 entire length of segment; maxillary palpi normal, four-segmented, segment 

 1 flattened, with distinct mesal projection, segments 2 and 3 cylindrical, 

 segment 4 minute, peg-like; labial palpi normal, three-segmented; larva- 

 pods located close together near the meson, proximal portion chitinized, seti- 

 ferous, distal portion small, membranous, non-setiferous, bluntly rounded, 

 those on seventh or eighth abdominal segment lacking membranous 

 distal portion. 



The genus is divisible into two sections by the structure of antennae and 

 number of larvapods. Owing to the incompleteness of published records 

 of larvae of this genus, involving in some cases confusion in specific identi- 

 fication, it is not possible to determine many of the specimens collected. 

 The following key will separate the species represented in the collections 

 studied. 



SPECIES OF HYLOTOMA 



1 (10) Antennae distinctly conical or peg-like, twice as long as wide; larvapods on abdominal 

 segments 2-6 and 10, seventh segment with rudimentary pair; head always uniformly 

 blackish, brownish, or yellowish; body always with numerous minute blackish spots 

 arranged longitudinally along subdorsal, dorso-lateral, supraspiracular and pedal 

 lines f 2. 



2(5) Head always black, thoracic legs with all segments blackish; tenth abdominal tergum 

 blackish 3. 



3(4) Tenth abdominal segment on ventral half blackish; area between larvapods with 

 minute colored spots; area ventrad of pedal folds with minute spots; latus of each 

 segment with a few very minute secondary setiferous spots besides regular tubercu- 

 late spots; on Crataegus Y-194-3 194-2; on Prunus? Y- 194-5 Hylotoma sp. 1. 



4(3) Tenth abdominal segment on ventral half unmarked, whitish; area between larvapods 

 without minute colored spots; area ventrad of pedal folds without minute spots; 



