196 
form a distinct and unexplained exception were it not for the fact that 
I fully believe the statement to have been unfounded. MHaliday, in 
speaking of plant-louse parasites (Entom. Mag. II, 99), writes: 
Some of these last [parasites of Aphidius] 
(Coruna 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 Westwood in his Introduction 
and by subsequent writers, and 
Buckton in Volume It of his Mono- 
graph of the British Aphides gives 
Fie. 20.—Pupx of Elachistus spilosomatis at- a somewhat elaborate, illustrated 
tached to shrunken larva of Spilosoma vir- account of the coccoon-spinning of 
ed ubire ca uwice)(orieiial)) a species which he calls C. dubia. 
He figures one cocoon broken open and showing several shining black 
pupee which he considers to be parasites of the Coryna. Coryna, it may 
be stated, is identical with the pteromaline genus Pachyerepis of 
Foerster. Now cocoons precisely similar to those described by Foerster 
and figured by Buckton are found in this country (Fig. 21). Miss 
Murtfeldt has found them 
under a rose Aphidid in 
Missouri, and Dr. Riley 
telis 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 Aphidid 
genus Praon, and, as it is 
quite out of the question 
that Praon should be hy- Fic. 21.—Cocoon of Praon, supposed formerly to be that of 
perparasitic upon Pachy- Coryna, under the body of a dead plant louse—enlarged 
erepis, we may safely con- — ©"8!"#)- 
clude that Praon makes the cocoon and that Pachyerepis (or Coryna) 
is a hyperparasite. It is more than likely that the several pupz 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 Braconid and 
not Chalcidid. We know then as yet no cases in which a Chaleidid 
larva transforms to pupa within a true cocoon. 
