ICHNEUMONID FINAL INSTAR LARVAE — SHORT 423 



but is not clearly papilliform; the closing apparatus of the spiracle 

 is separated from the atrium by a length of trachea approximately 

 equal to the depth of the atrium; the skin bears small setae and spines. 

 It is possible that Idiogramma should be placed in a subfamily 

 of its own since the shape of the mandible and the incomplete epistoma 

 separate this genus from other Tryphoninae. However, since the 

 epistoma is partly sclerotized dorsal to the anterior tentorial pits, a 

 labral sclerite is present, the antenna is not papilliform, and the 

 eggs are stalked, the genus has been placed with the Tryphoninae. 

 The structure of the spiracles and the presence of distinct spines on the 

 skin are characteristics similar to those of many Tryplioninae. The 

 characters of Idiogramma do not resemble those of any other sub- 

 family of the Ichneumonidae. 



Tribe Boethini 



Figure 13a 



Boethes sp. was examined. Members of this genus are parasitic on 

 the larvae of argid sawflies. 



All the head sclerites are present with the exception of the prelabial; 

 the labial sclerite is slender and its lateral parts meet the ventral 

 almost at right angles; each maxillary and labial palp bears two 

 sensilla, both round and one large and one small; two groups each of 

 four sensilla are present on the labrum; the mandibles are without 

 teeth; the antenna is disc-shaped with a prominent sensillum in the 

 center; the length of trachea separating the closing apparatus of the 

 spiracle from the atrium is almost equal to that of the closing appara- 

 tus; the skin bears large setae and small spines. 



Tribe Tryphonini 



Figure 13b, c 



Members of this tribe are parasites of the larvae of Tenthredinidae. 

 Polyblastus pedalis (Cresson) (CD A) (fig. 13b), Erromenus bedardi 

 Provancher (CD A), and E. dolichops Townes and Townes (CD A) 

 (fig. 13c) have been examined. 



All the head sclerites are present with the exception of the pre- 

 labial; the ventral part of the labial sclerite is pointed or curved so as 

 to give the sclerite an oval to round appearance; each maxillary and 

 labial palp bears three sensilla in Polyblastus and two in Erromenus; 

 the mandible is without teeth in Polyblastus but has small teeth in 

 Erromenus: the disc-shaped antenna has two sensilla; the distance of 

 the closing apparatus of the spiracle from the atrium is about equal 

 in length to the closing apparatus in Polyblastus, but the distance is 

 about twice the length of the closing apparatus in Erromenus: small 

 spines are present on the skin of both Polyblastus and Erromenus, but 



504675—59 3 



