INTRODUCTORY PAPERS ON ICHNEUMONIDJE. 179 



the parasitic larva leaves its host when full-fed and spins its own 

 cocoon, either within the cocoon of its victim — when this is a 

 cocoon-making species — or by the side of the dead larva skin, or 

 pupa, as is more frequent. 0. luteus occasionally spins its 

 cocoon within the pupa of its host. Mr. Bignell has con- 

 firmed Gravenhorst's observation in the case of Agrotis prcscox 

 pupa (cf. Ichn. Europ., iii. 693). Keaumur figured (ii. p. 435 ; pi. 35 

 and 37) the banded gold-beater's-skin-like cocoons, and minutely 

 describes the process of formation. The similar cocoon of 

 O. pteridis, Kriechb., ex the European Noctua — Eriopus pteridis, 

 Fabr., is figured in ' Pinacographia,' pi. 39, fig. 5 b. The more 

 common form of cocoon of 0. obscurum is figured on Plate ii., 

 fig. 8 : it is smooth, hard, cylindrical, 9 lines by 4, dark 

 testaceous, with a few threads of black silk running over the 

 surface. The irregularly cylindrical, shining chestnut-brown 

 cocoon of O. bombycivorus ex Stauropus fagi, from the New 

 Forest, is figured at Plate ii., fig. 10 : the outer envelope appears 

 to project out of the cylindrical shape of the inner one ; it 

 measures 8 lines by 5 ; there are but a very few silky hairs on the 

 cocoon. Vollenhoven describes the cocoon of 0. minutus as 

 obscure brown with a gray band, but not metallic in colouring. 

 The following species have been bred ; the common 0. luteus and 

 O. obscurus from many varied hosts ; while the fine and rare 



0. undulatus and others appear to be almost confined to the 

 larger Bombyces : — 



1. obscurus, Fabr., from Arge galathea ; Raynor. Sesia formicaeformis ; 



Brischke. Bombyx pini* ; (Reissig) Ratze- 

 burg. Dicranuravinula; Eedle. Pseudopterpna 

 cytisaria ; Brischke. Geometric! ; (Reissig) 

 Ratz. Acronycta leporina ; Drewsen aud 

 Boie. Pachetra leucophaea ; (Graff) Ratz. 

 Agrotis porphyrea ; Brischke. Hadenaprotea, 

 Epunda lichenea ; Bignell. 



2. luteus, L., from Sesia formicaeformis ; Brischke. Chelonia villica ; 



DeGeer. Bombyx pini* ; (Reissig) Ratz. 

 B. quercus ; Marshall Coll. Demas coryli ; 

 Brischke. Dicranura bifida ; Brischke. 

 D. vinula ; DeGeer, Grav., Curtis, &c. Cy- 

 matophora fiavicornis, Acronycta aceris ; 

 Brischke. A. leporina ; Bignell. Leucauia 

 lithargyria ; Butler. Dipterygia pinastri ; 

 Drewsen and Boie. Agrotis praecox ; Grav., 

 Bignell. Trachea piniperda; (Graff, Schmidt) 

 Ratz. Taeniocampa populeti ; Bignell. T, 



