COLOUR DIMORPHISM IN THE LARVA OF BRENTHIS EUPHROSYNE. 153 



The specimen is large, 34mm., against 32mm. of an ordinary 

 Hyeres 0. rubi J . The brown colour is very rich on the hinchvings, 

 the wings seem a little broader than in the type, and the anal angle of 

 the hindwing has no trace of the " tail." Beneath, the upperwing is 

 of a very blue-green, the under inclining to yellow. The white dots 

 are represented by a continuous narrow white line, wanting only on 

 that portion of the upperwing that is not green, as it is covered by the 

 lower in most positions. It is narrower than individual spots often 

 are in individuals spotted in the ordinary way. I captured a good 

 many specimens in hopes of getting another of this aberration, but 

 not only got none, but found nothing like an intermediate form. 



Colour dimorphism in the larva of Brenthis euphrosyne. 



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

 This spring, Mr. St. Quintin and Mr. Powell called my attention to 

 the occurrence, at Hyeres, of two forms of the larva of Brenthis 

 euphrosyne in about equal numbers, and Mr. St. Quintin provided me 

 with the larvae from which the following notes are made. I suppose 

 we are all familiar with the great range of colour and marking in the 

 larvae of, say, Aglais urticae and Pyrantels atalanta, and with the great 

 invariability of Vanessa io. It is curious that, as regards larva? which 

 we see more seldom, we are apt to classify them as to their stability of 

 colouring with such species as V. io rather than with P. atalanta. The 

 following notes may contain nothing new, but are interesting in the 

 aspect just alluded to. I do not know of any English reference to the 

 black spined form of this larva. 



Fullgroum larvae of Brenthis euphrosyne, Hyeres, April 8th, 

 1907. — The special point to be noted is the colour dimorphism; certain 

 larvae being black and others with yellow spines. Some of the larvae are 

 very large, as much as 35mm. long. The larvae are black dotted over 

 very equally with minute yellow points, which are probably pollen 

 grains and really nothing to do with the larvae. The spines are three 

 on each side, i ?, iii ?, and v ? Laterally, between iii and v, the 

 spiracular region, is a varying amount of bluish or bluish-white 

 marking. It looks as if it might in the extreme be a broad lateral 

 band from iii to v. An average specimen shows a patch on each side 

 of each incision at level of v that would be a line were it not divided 

 by incision and by spine v. There are much smaller spots just below 

 the level of iii, but similarly disposed on each side of the incision, 

 a patch round and chiefly below the spiracle, and many other minute 

 dots surrounding the bases of the black skin-hairs in this region. In 

 the blackest larvae these blue markings are much reduced, and there 

 only remains a spot or two of the lower series, a narrow ring round the 

 spiracle, and the skin-hair dots, but only below the spiracle. On the 

 black larva) the spines are also black, but with a pale tendency to the 

 bases of the dorsal series usually, as if the black material was in 

 insufficient quantity. Certain larvae, however, have the spines 

 brilliant yellow, producing a specially fine effect. The yellow spines 

 have the basal half, or a little more, yellow, the tips being black. One 

 larva has only the dorsal series yellow in this way, others have the 

 series of iii also so ; and rarely v is also yellow, as in a blown specimen 

 received from Mr. Powell. In the yellow larvae, however, the bases of the 



