68 BRITISH BUTTBRFLIEa 



Until very recently it had always been stated by en- 

 tomologists, that the Brimstone Butterfly was " double- 

 brooded" (a term meaning that it went through two whole 

 cycles of existence, from the egg to the perfect insect, in 

 one year), one brood appearing in May, and the other in 

 the autumn. 



But it is now established, on very satisfactory evidence, 

 that one brood only is produced, and that, the autumnal 

 tne. A considerable number of these survive the 

 *dnter in some place of concealment, and coming out 

 again in the spring form the so-called spring brood. 

 Many of these hybernators are found to be in very fair 

 condition in the spring, but in general they lack the 

 perfect freshness and bloom of those taken in autumn ; 

 the wings of those I have taken at this period are often 

 semi-transparent, from having lost feather, and fre- 

 quently are spotted and discoloured, as if by mildew ; 

 a sign probably of their owners having wintered in 

 damp lodgings 



Mr. Douglas states that they get very fat and full of 

 honey before consigning themselves to their long win- 

 ter's sleep ; evidently an instinctive provision against 

 the waste of substance that must of necessity accom- 

 pany all, even the most sluggish vitality : in this respect 

 following the same instinct that leads bears, and other 

 hybernating animals, to fatten up to their utmost stretch 

 uefore retiring for the season. 



The eggs should be sought for in the month of May, 

 or a little earlier or later, on the buds and young shoot* 



