ICHNEUMONID FINAL INSTAR LARVAE — SHORT 429 



6. Labial sclerite round in shape and with lateral parts not meeting ventral 



approximately at right angles Thaumatotypus 



Labial sclerite not round in shape and v/ith lateral parts meeting ventral 

 approximately at right angles Phygadeiion 



7. Mandible with teeth only on dorsal surface of blade 8 



Mandible with teeth on dorsal and ventral surfaces of blade '^ 11 



8. Teeth few in number and relatively large Bathythrix 



Teeth small and fine 9 



n. Two sensilla present on each maxillary and labial palp Otacustes 



Sensilla not as above 10 



10. Three sensilla, two large and one small, present on each maxillary and 



labial palp Mastms molefetae (Uchida) 



One large sensillum situated dorsally and two or three small sensilla situated 

 ventrally in the form of a crescent on each maxillary and labial palp. 



Thysiotorus 



11. Labial sclerite approximately circular in shape Etheiurgus 



Labial sclerite not approximately circular in shape; lateral parts meet ventral 



approximately at right angles 12 



12. Papillus of antenna reduced to disc bearing three sensilla Iselix 



Antenna not of this shape 13 



13. Two sensilla present on each maxillary and labial palp 15 



Sensilla not as above 14 



14. Two sensilla of equal size together with one or two smaller sensilla present on 



each maxillary and labial palp 18 



One large ventral sensillum and a dorsal group of smaller sensilla present on 

 each maxillary and labial palp Masfrus sniilhii (Packard) 



15. Dorsal sensillum on each maxillary and labial palp larger than ventral. 



Endasys 



Dorsal sensillum on each maxillarj' and labial palp smaller than ventral or 



equal in size to ventral 16 



16. Pleurostoma more lightly sclerotized than hypostoma. 



Gelis tantillus (Cresson) 

 Pleurostoma as well sclerotized as hypostoma 17 



17. Labral sclerite with single median expansion Heniiteles 



Labral sclerite not expanded in its median part and with two small dorsolateral 



expansions Mastrus argeae (Viereck) 



18. Mandible with rounded base and relatively short blade. 



Gesis bruesii (Strickland) 

 Mandible with a conical base and relatively long slender blade . . Phobetes 



Of the characters used in the above key, the form of the labral 

 sclerite and its degree of sclerotization is not a good one. In some cases 

 the character is clear, but in others it may be obscured when the entire 

 length of the sclerite has not been forced into the one plane during 

 mounting. However, since the tribe is extremely uniform and the 

 labral sclerite does differ in shape and degree of sclerotization in dif- 

 ferent genera, it was found necessary to use this character. 



" Teeth on the ventral surface of the blade of the mandible are usually very small and must be looked for 

 with great care. 



