ICHNEUMONID FINAL INSTAR LARVAE — SHORT 407 



lightly sclerotized ; the hj^postoma is well sclerotized and in Oxyrrhexis 

 and Acrodactyla (Beirne, 1941) is expanded at the posterior end; 

 the hypostomal spur is well sclerotized, as is the stipital sclerite which 

 is expanded at its posterior end in Hymenoepimecis and Oxyrrhexis; 

 the labial sclerite is roughly square in shape in Zatypota but roughly 

 triangular in other genera, although the ventral part of the sclerite 

 is pointed in Zatypota and Acrodactyla; the maxillary and labial 

 palps each have one sensillum in Hymenoepimecis, Oxyrrhexis and 

 Acrodactyla, but there are two sensilla to each palp in Zatypota; 

 the labral sclerite is lightly sclerotized in its lateral parts but is 

 unsclerotized dorsally; the mandible is slender and small teeth are 

 present on the dorsal surface of the blade ; the antenna is papilliform ; 

 the closing apparatus of the spiracle is close to the atrium ; long setae 

 are present on the skin; spines, which appear to serve as holdfast 

 organs, are present on the dorsal surface of some body segments. It 

 is not possible to distinguish the precise distribution of these spines 

 from cast skins. Nielsen (1923, 1935, 1936) figures and describes 

 the distribution of these spines in the tribe but gives no adequate 

 figure of the head structure of the larvae. 



Larval Key 



1. No enlargement present on posterior part of hypostoma . . Hymenoepimecis 

 Enlargement present on posterior part of hypostoma 2 



2. Lateral end of stipital sclerite expanded Oxyrrhexis 



Lateral end of stipital sclerite not expanded . '. ... 3 



3. Ventral part of labial sclerite with small dorsal projection into prelabial 



area Zatypota 



Ventral part of labial sclerite without dorsal projection .... Acrodactyla 



The following have been examined: Hymenoepimecis sp. (fig. 5a), 

 Oxyrrhexis carbonator texana (Cresson) (fig. 5b), and Zatypota sp. 

 (fig. 5c). Acrodactyla degener (Haliday) is figured by Beirne (1941). 



Tribe Pimplini 



Figures 6, 7 



The members of this tribe are endoparasites of a variety of lepi- 

 dopterous pupae. 



The head sclcrites are distinctive in that they appear to form a 

 ring around the mouth. The epistoma is well sclerotized, except in 

 Xanthopimpla; the pleurostoma is well sclerotized and the hypostoma 

 is short in most species; the hypostomal spur is well sclerotized and 

 the stipital sclerite is short in most species; the labial sclerite is longer 

 than wide with thin lateral parts and a broadened ventral part; 

 the mandible is relatively large and has no teeth on the blade; the 

 labral sclerite is absent and in some genera the sensilla of the labrum 



504675—59 2 



