tORKSHIKK ABERRATIONS OF ABRAXAS SYLVATA (uLMATa). 69 



the larvffi were in great profusion in the autumn of 1896, and mal- 

 nutrition is suggested as being responsible for the occurrence of this 

 unusual and rare form here. I remember, however, a similar abund- 

 ance of larva) eight years ago, when the elms were stripped in a great 

 measure, and larvae in numbers might be seen hanging from the leaves 

 and branches, but my visit to the wood the following year revealed 

 nothing out of the ordinary amongst the specimens 1 examined at 

 rest. We ought to have found, had malnutrition worked out as it 

 usually does in reducing the size of the imago, many dwarfed examples, 

 but this was not actually so; they were the exception, and very few 

 were noticed, the specimens being generally of the normal size. The 

 very large percentage of cripples of the ab. .s?<//».sa has been already 

 referred to, but what was very striking was the inability of the fully- 

 developed examples of the darkest form to fly to any extent. I believe 

 only one or two were actually taken in flight ; the superabundance of 

 what appears to be slaty-blue pigment seemed to make them more 

 sluggish than the type form, which generally took wing when disturbed, 

 and made oft'. Mr. Tutt remarks that apparently the best of Mr. 

 Dutton's specimens had undergone a flattening out by the setting 

 brace, as the wings appeared more or less crumpled. This was exactly 

 the case with my specimens of the extreme form, and, when on the 

 board, the wings when pressed in one part bulged out in another, just as 

 if air or liquid was being pressed. Aneurism was not uncommon, and 

 in one specimen, which I accidentally punctured with the setting- 

 needle, the bleeding was very apparent. The suft'usion of the slaty- 

 blue colour is not, as Mr. Tutt points out, caused by an increase of 

 the area of the usual shading of the wings, but by the spread of the 

 leaden colour, which permeates the body as well, and is not readily 

 rubbed oft" the wings like the ordinary scales, but remains a dirty blue 

 when the wing scales have been removed. 



In considering the abnormal appearance of the aberrations under 

 notice, the fact of dark forms appearing side by side with an unusually 

 large number of the extremely light form, and both of normal size, 

 should not be lost sight of by those who study the probable causes of 

 variation. I need not add to the speculations indulged in as to the 

 immediate continuance of this grand form and its intermediates by 

 descent, as time will soon settle that point. 



Habits of Abraxas sylvata (ulmata). 



By J. E. EOBSON, F.E.S. 



The notes by Messrs. Hewett and Tutt in The Entowolot/i fit's Record 

 (vol. ix., pp. 304-7), suggest to me that the habits of this species are 

 not well known. Stainton {Manual, vol. ii., p. 65) says : " Abra.ias — 

 pupa in a slight web amongst trees." This is correct in respect of A. 

 (frossulariata, the larva of which spins a sort of hammock, in which it 

 changes to a pupa. The larva of A. si/lrata {ulniata) behaves very 

 difi'erently, and also difterently from the larva? of most tree-feeding 

 species. These generally descend the tree-trunk when full-fed, and 

 enter the ground, in close proximity to the trunk, to pupate. When 

 the larva of A. ulmata reaches maturity, it attaches a thread to the 

 twig on which it is feeding, and descends by this to the ground for pu- 



