324 THE entomologist's record. 



visitations. Hundreds were bred by those who treated the pupte arti- 

 ficitilly, yet, in 1889, the insect was entirely absent in those locahties 

 in which it had been so abundant the previous summer and autumn. 

 Since then there has been no "7>. <iaUi " year in Britain, although a 

 few examples were recorded in 1897.. 



In cases such as that just described, we have an instance of a moth 

 that can only be considered as an " occasional " British species. There 

 are, however, other moths, which have a more or less permanent 

 habitat in our Islands, but whose numbers are now and again reinforced 

 by immigrants, much to the advantage, undoubtedly, of the native 

 race. 



One of these is the usually common Pltisia (jcuxiua. Probably a 

 season rarely passes without some immigration of this species taking 

 place and, in some seasons, vast numbers undoubtedly arrive. It must 

 not be overlooked that most moths fly by night, when it is quite 

 impossible to see their movements ; our conclusions, therefore, are 

 based rather on indirect than on direct evidence of the fact. But 

 these conclusions are undoubtedly correct in very many instances. One 

 fine May morning in 1892, we were in Chattenden woods near 

 Rochester. The ordinary butterflies and moths appearing at that time 

 of year in that locality were observed. We spent several hours in the 

 wood and never saw a specimen of 1\ (janwia. The next day, we 

 walked over the same ground, and every footstep stirred up numbers of 

 imagines of this species. Thousands were there, and we noticed then 

 that many of the specimens were exceedingly pale, a striking 

 characteristic of the south European examples which we have fre- 

 quently observed. In the course of the next few days, we were 

 inundated with letters from various parts of the country, recording the 

 sudden appearance of this moth on that particular day. They swarmed 

 even in our London gardens. Whence came they ? 1\ ijamma had 

 been comparatively rare in Britain the previous autumn. The pale 

 tint and ragged wings of some of the specimens suggested that they 

 were of the south European form, and not recently emerged, and there 

 can be no reasonable doubt that on the night preceding our second 

 visit to Chattenden Woods there had been an extensive immigration 

 of this species. 



This moth has been chosen as an example to illustrate the par- 

 ticular phenomenon exhibited by a sedentary moth increased in 

 numbers by immigration, because sudden appearances of this kind are 

 not at all infrequent in the case of this species, and every observer will 

 almost certainly, in the course of a very few years, be able to test the 

 facts and draw conclusions for himself. 



[To he continued.) 



Dehiscence of the female pupa of Fumea casta (iiitermediella). 



By T A. CHAPxMAN, M.D., F.Z.S., F.E.S. 



The $ of Fumea casta {uitcrwcdidla) after emergence sits at the 

 end of her case, with the extremity of the abdomen applied to the 

 opening of the pupa-case, into which she is afterwards to place her 

 eggs ; she is in many respects so helpless that one jumps to the con- 

 clusion that she does so to enable her to keep in touch with it, and 

 not to lose knowledge of where it is. She raises the extremity of the 



