11)6 



form a distinct aud unexplained exception were it not for the fact that 

 I fully believe the statement to have been unfounded. Haliday, in 

 speaking of plant-louse parasites (Entom. Mag. II, 99), writes: 



Some of these last [parasites of Aphidius] 

 {Coriina clavata Walk., Ent. Mag, I, p. 386), 

 not content with the covering which pro- 

 tects the Aphidius to its final change, when 

 they are full fed leave the cavity and spin 

 a white silky web between the belly of the 

 Puceron and the leaf, and in this undergo 

 their transformation. 



This statement has been quoted 

 by West-wood in his Introduction 

 and by subsequent writers, and 

 Buckton in Volume ii of his Mono- 

 graph of the British Aj)hides gives 

 ^ „„ ^ ^ ,,, ,. ., . . Ji somewhat elaborate, illustrated 



Fig. 20. — PupsB of Elachistus spilosomatis at- ' 



tached to shrunken larva of Spilosoma vir- aCCOUUt of the COCCOOn-Spiuning of 

 iriHica, enlarged twice (original). .^ SpeciCS which he Calls C. flubia. 



He figures one cocoon broken open and showing several shining black 

 pupte which he considers to be parasites of the Coryna. Coryna, it may 

 be stated, is identical with the pteromaline genus Pachycrepis of 

 Foerster. Now cocoons precisely similar to those described by Foerster 

 and figured by Buckton are found in this country (Fig. 21). Miss 

 ^lurtfeldt has found them 

 under a rose Aphidid in 

 Missouri, and Dr. Riley 

 tells me that he has seen 

 them abundant under 

 dead Aphidids upon his 

 rose bushes in Washing, 

 ton. We breed from these 

 cocoons here, not Pachy- 

 crepis, but the Aphidiid 

 genus Praon, and, as it is 

 quite out of the question 

 that Praon should be hy- 

 perparasitic upon Pachy- 

 crepis, we may safely con- 

 chide that Praon makes the cocoon and that Pachycrepis (or Coryna) 

 is a hyperparasite. It is more than likely that the several pupae of 

 the unknown secondary parasite figured by Buckton are those of Coryna 

 itself, while the larva which he watched so carefully under glass, and 

 figured in the act of making its cocoon, was undoubtedly Bracouid and 

 not Chalcidid. We know then as yet no cases in which a Chalcidid 

 larva transforms to pupa within a true cocoon. 



Fig. 21. — Cocoon of Praon, supposed formerly to be that of 

 Coryna, under the body of a dead plant louse— enlarged 

 (original). 



