LARENTID.E^PHIBALAPTER YX. 333 



iti5 fecundity is very great, there appear to be uo definite 

 bounds to its increase. Five or even six generations in a 

 year appear to be no verjr unusual circumstance with it ; it 

 passes the winter, successfully, with us, in the moth state ; 

 and the eggs laid by a spring captured female are nearly sure 

 to be fertile ; the resulting larvae are, in confinement, quite 

 healthy, and almost every pupa produces a moth — so that the 

 fortunate captor of a specimen may fill his own series and 

 those of all his friends with its descendants in a single season 

 — and yet, out of doors, this is always a rare species. There 

 are indeed indications that from time to time it actually cpiite 

 dies out here, and is only re-introduced in the course of 

 natural migration. So rare was it fifty years ago that even 

 so late as the date of Stainton's Manual the sexes were 

 looked upon as separate species, the female being known as 

 (jcmiiuivia, and the capture of three or four specimens only, of 

 each, was on record. The earliest of these seems to have 

 been taken upwards of a century ago, at Peckham, in the 

 suburbs of London. About the year 1856 a small immigra- 

 tion appears to have taken place, for specimens were taken in 

 Devon, Somerset, the Isle of Wight, and again in the London 

 suburbs ; and as eggs were now obtained, and reared, the 

 identity of the two forms was quickly established. From 

 this time until 1880 it continued to be taken occasionally in 

 the London suburbs, and extended widely over the country, 

 contituung always to be a rarity at large, though perhaps less 

 so in the south-west of England than elsewhere ; but after 

 the latter date it almost disappeared, and lias since been re- 

 presented only by casual specimens in isolated \-ears, until the 

 last year or two, when again a few have been captured. There 

 is not the smallest reason to suppose that it may have been 

 rendered more rare, or exterminated, by over collecting : its 

 habits do not admit of this, since it is very far from gregarious, 

 and well able to take care of itself ; and there is in my own 

 mind no question that some influence with wiiich we are un- 

 acquainted, either of weather or of parasites, is responsible here 



