50 THE ENTOMOLOGIST. 
frequently, that even small records, or notes, are always of 
interest to some: while their publication frequently develops 
friendly controversy, from which facts of value may be elicited, 
tending towards an increased knowledge of the economy of the 
great class Insecta. 
Joun T. CARRINGTON. 
Savage Club, Savoy, London, W.C., 
February, 1886. 
LYCZNA ARGIOLUS BOTH MONOGONEUTIC AND |. 
DIGONEUTIC. 
By J. Junner Weir, F.L.S., F.Z.S., V.-P.E.S. 
Lycena argiolus is, to my mind, the most interesting butterfly 
we find in England ; for many years I have paid great attention 
to the habits of the species, and my last communication on the 
subject may be found in the ‘Entomologist’ for 1884, pages 
193 to 197. 
Mr. Harcourt Bath’s note (Entom. 13) was very welcome 
to me, confirming, as it did, my own experience, that where the 
holly alone was found, L. argiolus was single-brooded or monogo- 
neutic, and that when the insect fed as a larva upon the ivy alone, 
or perhaps upon both holly and ivy, it becomes double-brooded 
or digoneutic. I wrote to Mr. Harcourt Bath, and, finding from 
him that he proposed to send a further account to the ‘ Entomo- 
logist,’ [ waited till he had done so before again taking up the 
matter. 
In the case of Pieris napi, and in the American species closely 
allied to L. argiolus, whether they are monogoneutic or digoneutic 
appears to depend entirely upon the length and warmth of the 
summer months in their habitats; this fact was particularly dwelt 
upon by me in my communication to the ‘Entomologist’ in 1884 
(Entom. xvii. 198), so far as the latter species was concerned ; 
with regard to the former species, Pieris napi, v. bryonie@, the 
alpine form, is single-brooded, and in Lapland and the Arctic 
regions it is also monogoneutic. All this is clearly understandable 
on Weisman’s view —that Bryonie@ is the original form, and that 
by the amelioration of the climate a summer brood has been 
interpolated. 
But this explanation will not meet the case of L. argiolus 
