822 MAUD D. HAVILAND 



Pachycrepis clavatii, Wlk., is included in the allied 

 tribe Pachyneurini, which Ashniead say« are regarded as 

 chiefly parasites of the same Ehynchota, but he adds that 

 these insects have other hyinenopterous parasites, through 

 which the Pachyneurini are probably hyperparasitic. 



In addition to Asaphes and Pachycrepis, two 

 females of a species of Pachyneuron were reared. The 

 eggs and early larval stages of the two former species are 

 indistinguishable. The egg of the Pachyneuron is charac- 

 teristic, but its development was not observed. 



Various Chalcidae have been recorded as reared from 

 aphides, and it is possible that some of them may yet prove 

 to be primary parasites ; but the forms described here are 

 hyperparasites of the plant-lice through the larvae of Aphi- 

 d i u s , and allied genera of Braconidae, wliich develop internally 

 in aphides. The Chalcidae do not oviposit until the aphid is 

 dead and the Aphidius has woven its cocoon, and is ready 

 to transform inside the empty skin of its late host. Their 

 true relation to the aphid was shown as long ago as 1834 by 

 Nees ab Esenbeck for Asaphes or a similar form, and his 

 observations have been confirmed by Walker and Buckton, 

 and subsequently by other writers. 



These hyperparasites do not appear to be specific for different 

 Aphidiidae or aphides. In 1919 1 reared Asaphes vulgaris 

 from an Aphidius in Ehopalosiphum s one hi, 

 Kalt., and also from Aphidius salicis, Hal., a parasite 

 of Aphis saliceti, Kalt. This Braconid and aphid are 

 less than half the size of A. ervi and M. urticae, but 

 the Chalcid seems to adapt itself to either form, and thus 

 probably has considerable latitude in the choice of a host. 



Pairing. 



All observed ovipositions of Asaphes and Pachy- 

 crepis took place after pairing. Only two examples of 

 Pachyneuron were obtained, and both were females. 



One laid a single egg parthenogenetically and died soon after- 

 wards. The other lived for some days but did not oviposit. 



