427] LARVAE OF THE TENTHREDINOIDEA—YUASA 109 



affinities with both the Cephidae and Xiphydriidae and on the basis of 

 venation, it probably belongs to the latter as denned by MacGillivray. 

 Certain features other than venation, however, led Rohwer to place it in 

 the Cephidae. It is not safe to venture any opinion without careful 

 examination of the larvae, but their antennae and their lack of papilliform 

 subanal appendages suggest close affinity with the Xiphydriidae. 



At least six out of sixteen American species have been recognized 

 in the larval stages and their host-plants recorded. Janus integer and 

 Cephus cinctus are economic pests. Konow's tribe Macrocephides includes 

 the species whose larvae bore into the pith of shrubs and woody twigs, 

 and his tribe Cephides embraces those whose larvae bore into the stalks 

 of Graminaceae. 



Middleton (1917) published descriptions and keys for distinguishing the 

 larvae of five species representing four genera, Adirus, Janus, Cephus, and 

 Hartigia together with a definition of the groups based on "characters 

 common to all the genera studied and probably to the family." He 

 reserved for future discussion the question of the systematic position of 

 the Cephidae, but pointed out the obvious affinity of this group with the 

 Siricidae on one hand and the Pamphiliidae on the other. Gahan (1920) 

 described the larva of Tracheitis tabidus (Fab.) and added a key for sepa- 

 rating this larva from that of Cephus cinctus and C. pygmaeus. 



GENERA OF CEPHIDAE 



1(10) Papilliform subanal appendages present on the ultimate abdominal segment 2. 



2(3) Suranal process depressed on the distal portion, oval in cross-section, with strongly 

 chitinized dentiform tubercles on the proximal portion; antennae five-segmented. 



Janus Stephens. 



3(2) Suranal process not depressed on the distal portion, circular in cross-section, with or 

 without strongly chitinized dentiform tubercles on the proximal portion; antennae 

 four-segmented 4. 



4(5) Suranal process proximad of distal cylindrical portion with strongly chitinized 

 dentiform tubercles Adirus Konow. 



5(4) Suranal process proximad of distal cylindrical portion without strongly chitinized 

 dentiform tubercles 6. 



6(7) Terga of eighth and ninth abdominal segments setiferous, each with a transverse row 

 of distinct setae; tenth abdominal tergum as viewed from side strongly convex and 

 truncate on the caudal aspect; suranal process with stiff setae not arising from distinct 

 chitinized bases Trachelus Jurine. 



7(6) Terga of eighth and ninth abdominal segments glabrous, each without a transverse 

 row of distinct setae; tenth abdominal tergum as viewed from side not strongly 

 convex and not truncate on the caudal aspect but gradually declivous caudad; 

 suranal process with stiff setae arising from distinct chitinized bases 8. 



8(9) Suranal process with distal chitinized portion very short and ring-like, or very 

 long and cylinder-like, more than twice as long as wide; suranal process with a 

 single transverse row of setae proximad of the distal chitinized portion or with two or 

 more whorls of setae; the distal margin of the distal chitinized portion not distinctly 

 serrate Cephus Latreille. 



