42 The Irish Naturalist. April, 



SOME FORMS OF PIERIS NAPI TAKEN IN COUNTY 



FERMANAGH. 



BY SIR CHARLES LANGHAM, BART. 



In the following list I have endeavoured to describe the 

 various forms of Pieris napi which I have taken in this 

 district during the past few years. The spring, summer 

 and autumn of 1921 were very favourable to this butterfly. 

 I never saw so many in any other year ; they were literally 

 swarming in places, especially on wet low-lying ground. 

 The butterfly first appeared on April 20th and they continued 

 with only a short break up till October 15th on which day 

 I saw a newly emerged male. As this butterfly is usually 

 nearly over by the end of x^ugust, one cannot help thinking 

 that the swarms one saw in September and the beginning 

 of October formed a partial third brood of the year ; the 

 fine hot weather inducing insects to emerge that should 

 have remained in the pupal state until April following. This 

 was the only butterfly that was numerous here last summer, 

 other common species being decidedly scarce : except 

 Vanessa atalanta, which although usuall}/ very rare here 

 appeared in some numbers in the autumn. 



I have so far never come across the var. Jlava of Pieris 

 napi, though I have been on the look-out for it for years, 

 any yellow specimens I have obtained being nothing like 

 such a bright yellow as Mr. Kane's insect, which is now 

 in the Natural History collection of the National Museum 

 in Dublin. There is in both sexes a good deal of variation 

 in the size and shape of the wings, especially in the hind 

 wings, also in a great many specimens there is a very 

 distinct darker spot in the apical blotch ; this spot is not 

 mentioned in the description of P. napi in any book I have, 

 and in my English specimens it does not show up so clearly 

 as in the Irish insects ; in the list of forms given below 

 I have not taken this spot into account except in No. 4 of 

 the females ; in this specimen the spot is so very distinct 

 that I had to mention it. Taking the forms of the male 

 butterfly first : — 



