276 THE ENTOMOLOGIST. 



species that without bright sunshine is very likely to be over- 

 looked. 



The appearance of gamma coincides very closely indeed with 

 that of cardui, and the abundance of noctuella above referred to 

 is a factor that must not be disregarded. Both cardui and gamma 

 are known migrants, and there is good reason for believing that 

 noctuella should be included in the same category. Such evidence 

 as we have with regard to this autumn's visitation may confirm 

 Mr. Mathew's suggestion {ante, 267) so far as concerns the im- 

 mediate cause, but we must look much further than the mere 

 prevalence of easterly winds in our immediate neighbourhood 

 for the primary cause, and I think the true solution will be found 

 in the migratory habits of the species in question. 



Lewisham : Oct. 17th, 1903. 



PLUSIA NI AT PENZANCE. 



By William Daws 



(Late Curator of Forth Enys Museum). 



I WAS interested in seeing Dr. Knaggs's' account of this insect 

 at Lynwood, near Penzance {ante, p. 217). The reason the late 

 Mr. Baily did not make the matter known through the entomo- 

 logical magazines was that it had been hinted that he had intro- 

 duced the species, and this caused him a great deal of annoyance. 

 He told me he should keep quiet until someone opened the sub- 

 ject ; then he would discuss it with them. I wish Dr. Knaggs 

 had published his note sooner, as it would have given Mr. Baily 

 a chance to place the facts before the public. P. ni was first 

 taken at Lynwood by Mr. W. Beeton, who was staying there on 

 a visit ; he did not know anything about entomology, so used to 

 bring in anything in that line that he found. I do not remember 

 the number that was bred from larvae brought in by the work- 

 men ; Mr. Baily gave a reward to them for each P. ni reared. 

 Each man had a separate breeding-cage, with his name on; they 

 collected all the green larvae they could find feeding on the cab- 

 bages in their gardens. Some of the gardens were three-quarters 

 of a mile from one another. Mr. Baily supplied several friends 

 and collectors with specimens. I believe a pair that he gave to 

 Mr. C. Briggs was sold at Stevens's for £4 Is. Through the kind- 

 ness of Mr. Baily I have a series of four in my collection. The 

 gamma-like mark in P. ni varies in size and definition. The 

 larva of P. ni can easily be separated from that of P. gamma : it 

 has a more slender appearance than the larva of P. gamma. The 

 cocoon is quite white, and the pupa is black and not so robust as 

 the pupa of P. gamma. Mr. Baily did not make a collection of 

 pupa-cases or cocoons, so no care was taken of them ; but I have 



