534 



HYMENOPTERA 



FIG. 351. Helorus anomalipes. 

 Britain. 



ently a continuation of the tip of the body. The earlier stages 

 are passed in the bodies, or in the eggs, of other Arthropods. 



The Proctotrypidae is one of the most difficult groups of 



Hymenoptera to define ; some of its 

 members exhibit a great resemblance 

 to Aculeate Hymenoptera. This is 

 the case with the Insect we figure 

 (Fig. 351). It, however, is an 

 undoubted Proctotrypid, but there 

 are other forms that approach very 

 closely in appearance to the Acu- 

 leata, or stinging Hymenoptera ; so 

 that until a better comprehension 

 is reached as to the distinction 

 between a sting and an. ovipositor 

 the separation between Proctotry- 

 pidae and Aculeata must be con- 

 sidered somewhat arbitrary. 



There is extreme variety in the family ; the wings differ 

 considerably in shape and neuration ; they are not infrequently 

 altogether absent in one or both sexes. The chief distinction of 

 the family from other parasitic Hymenoptera is the tubular form 

 of the ovipositor ; which part appears to be a continuation of the 

 tip of the body. This latter is more definitely acuminate than 

 usual, and has given rise to the term Oxyura, by which name 

 the Proctotrypidae are distinguished in many books. From the 

 Chalcididae they are distinguished also by the angles of the 

 pronotum attaining the tegulae. In this character they agree 

 with the Cynipidae, but the ovipositor and abdomen are very 

 different in form in these two groups, and the Proctotrypidae 

 very frequently have a pigmented spot or stigma on the front 

 wings which is absent in Cynipidae. As if to add to the diffi- 

 culties the systematist meets with in dealing with this family, 

 some of its members have the trochanters undivided, as in the case 

 of the stinging Hymenoptera. The larvae of all that are known 

 lead a completely parasitic life in the bodies or eggs of other 

 Insects or of Spiders. Sometimes half a dozen specimens may 

 find the means of subsistence during the whole of their develop- 

 ment in a single Insect's egg. Usually Proctotrypids pupate in 



