92 ILLINOIS BIOLOGICAL MONOGRAPHS [410 



body becomes colorless and glabrous; free leaf -feeders; sometimes gregari- 

 ous. 



The Blennocampinae as restricted by MacGillivray is a large sub- 

 family rich in genera and species, and is related to Fenusinae and Scolion- 

 eurinae. This is in agreement with Konow's statement altho this author 

 makes his tribe Blennocampides the third in his subfamily Tenthredinini. 

 Rohwer would group the majority of the genera under consideration in 

 his subfamily Empriinae, but take out the genera Phymatocera and Tomos- 

 tethus from the subfamily and place them in a subfamily by themselves. 

 This arrangement has an advantage in classifying the larvae because of 

 the fact that the larvae of Tomostethus lack the characteristic spines which 

 readily distinguish the Blennocampinae from all other groups in the larval 

 stages. The following key will separate the genera examined, with two addi- 

 tional ones, Erythraspides and Periclista, whose diagnostic characters 

 are taken from Dyar's paper (1898b). 



GENERA OF BLENNOCAMPINAE 



1(2) Body without spines; with six annulets, annulets 2 and 4 each with a transverse 

 row of minute but stalked glandubae Tomostetltus Konow. 



2(1) Body with spines 3. 



3(10) Third abdominal segment with six distinct annulets; spines usually unbranched but 

 conical if branched, very short and minute, tenth abdominal tergum with small 

 conical unbranched spines 4. 



4(7) Body spines conical and not bifurcate, blackish 5. 



5(6) Spiracles with distinct black wings M onopkadnus Hartig. 



6(5) Spiracles without distinct black wings Hypergyricus MacGillivray 



7(4) Body-spines not conical but bifurcate, blackish or whitish 8. 



8(9) Spines whitish; tenth abdominal tergum not marked Blennocampa Hartig. 



9(8) Spines black; tenth abdominal tergum marked with black. .Erythraspides Ashmead. 

 10(3) Third abdominal segment with five annulets, rarely apparently with four; spines in 



part usually bifurcate, long, never short and conical 11. 



11(12) Tenth abdominal tergum with a mesal spine cephalad of caudal marginal row of 

 spines; subdorsal spines of prothorax with five branches; prothoracic spinal formula: 

 5-2-1:5:1-2; third abdominal segment:2-2-2K):3-2-2:2-l:l-2; ultimate tergum 1-1-1: 



2:2 Monophadnoides Ashmead. 



12(11) Tenth abdominal tergum without a mesal spine cephalad of caudal marginal row of 



spines; subdorsal spines of prothorax with three branches at most 13. 



13(14) Second annulet of third abdominal segment with three spines dorsad of spiracular 

 line; host-plants not confined to Quercus species; prothoracic spinal formula: 2-2-2: 



2-3:1-2; third abdominal segment 2-2-2:1:2-2-2:2-1:1:1 Isodictium Ashmead. 



14(13) Second annulet of third abdominal segment with two spines dorsad of spiracular 

 line; host-plants confined to species of Quercus; otherwise resembling the preceding 

 genus Periclista Konow. 



Tomostethus Konow 

 Larvae moderately large, length 17-21 mm., rather robust, yellow- 

 ish white; body subcylindrical, tapering little caudad, venter flattened, 



