COSMOTRICHE POTATORIA. 175 



margin rather than by the two lateral lips, which are distinct in most male pupae 

 (compare fig. 2). The relation to the limits of the 9th and 10th abdominal 

 segments is carefully figured. 



Dehiscence. — Pupal dehiscence takes place by means of a 

 slit along the thoracic mediodorsal line extending as far back as 

 the end of the mesothorax, as far forward as the raised point on 

 the - dorsal headpiece, and laterally along the ridges originating 

 at this point as far as the glazed eye, passing along the antenna 

 to some little distance beyond the junction of the pro- and meso- 

 thorax, and extending also between the pro- and mesothorax. This 

 leaves the prothorax apparently unattached, but it does not fall 

 out, being apparently held in position by some of the interior 

 membranes (Bacot). 



Foodplants. — Almost omnivorous but especially affects grasses 

 and rushes (Chapman), striped riband grass (Sutler), Dactylis 

 glomerata (Daltry), seeds of Juncus and grasses (Dalglish), heather 

 (Kane), grass, bilberry (G. O. Day), bramble (Lane), Triticum repens 

 (Brown), Arundo phragmites (Kerry), Digraphis arundinacea ^Christy), 

 Luzula (Rossler), Brojnus, Aiopecurus agrestis (Trimoulet), whortle- 

 berry (Fuchs teste Rossler), Holcus lanatus, Carex (Lambillion), 

 Trifolium and grasses (Riihl), Leontodon taraxacum, &c. (Heylaerts), 

 Bromus sterilis, Alopecurus pj'atensis, Phragmites communis, Carex 

 paniculata, C. ripa?'ia, C. caespitosa (Paux). 



Parasites.* — Pimpla instigator, Fab. (Bairstow), Pimpla gram- 

 inellae\, Schr. (Fitch), Rhogas geniculator, Nees, this species attacks 

 larva and emerges from it while resting on a twig apparently prepar- 

 ing for 4th moult i (Bignell), [Phogas circumscriptus, Nees (Bignell)], 

 Polysphincta varipes, Gr. (Billups), Exorista vulgaris, Fallen (Porritt). 

 A cocoon of C. potatoria found on dead twig of yew on downs near 

 Chichester about Aug. 5th, 1867, contained a pupa of the moth 

 filled with pupae of Nemoraea (Tachina) puparum, which emerged 

 between August 5th-i2th (Jeffery). 



Habits and Habitat. — The males fly actively by night and 

 come freely to light from about 9.30 p.m. to n.o p.m., and 

 possibly later, and one rarely sees them at all during the day. Dalglish, 

 however, unexpectedly notes that, in western Scotland, the males some- 

 times fly in bright sunshine and that he has seen them battling in a 

 heavy shower of rain. Hewett observed a pair, in cop., on the evening 

 of July 25th, 1900, the moths remaining united until the early part 

 of the next evening, at- York. The female commences to fly as 

 soon as it is really dusk, the mode of flight being particularly 

 heav 7 y, and one frequently hears her buzzing among the sedges, 



* Rhogas reticulator, Nees, has been recorded in error as having been bred 

 from the larva of C. potatoria (Bignell). 



t Bignell has a note that Fenn bred 23 examples of this species from C. 

 potatoria (in litt.). 



J Bignell notes : Bred from young larvse of C. potatoria, June 25th, 1880, 

 all the transformations taking place within the skin of its host before the 4th moult. 

 The larva of C. potatoria prepares for this moult by the usual method of covering 

 the twig on which it is resting with silk, and from that spot it never moves ; the 

 parasitic larva within then consumes the caterpillar, which gradually shrinks 

 in length, and, in about 3 weeks, R. geniculator emerges from a hole cut out of 

 the upper side of the nth and 12th segments; it does not appear to make a 

 cocoon within the larva, but takes advantage of the larval skin of potatoria for its 

 protection (in litt.). 



