KUKALIS BETULiE. 301 



be attached to the cardboard surface by some glutinous substance, but 

 were quite clear of the sloe leaves, although some of the latter, being 

 in front of them, afforded partial concealment. The attachment of 

 the pupa? was quite firm." Wood writes (in lift.): " The day previous 

 to actual pupation, the three larvae under observation crawled about in 

 their confined space in their characteristic sluggish manner. One 

 which had left its foodplant on the evening of July 14th, 1907, showed 

 at noon od the following day first perceptible change of colour. Its 

 bright green hue now had spread over it a reddish glow, the segmental 

 furrows, lower segmental area, and greater portion of head-parts, 

 however, still retaining the greenish hue. At 6 p.m. the reddish 

 coloration had become more pronounced, and the larva appeared now 

 of a general sickly, translucent, reddish hue. By 6 a.m. the following 

 morning this had now assumed the final deep reddish tint, and at 5 p.m. 

 on the 17th, the larva had lightly spun two fallen leaves of the foodplant 

 together at the bottom of a box and was hidden from sight, except 

 that a portion of the dorsal area (of the first few abdominal segments) 

 could be seen through a chink between the leaves. These leaves were 

 dead and dried, and concave on that side facing the bottom of the box. 

 The larva was attached in this concave fold belly upwards. Of the nine 

 larvae upon which I made further observation, six were allowed to remain 

 on leafy twigs of the foodplant placed in a bottle in a large earthenware pan, 

 the bottom of which was covered with 2ins. of earth (for I was anxious 

 to know if pupation ever actually took place below the surface of the 

 earth), and the other three were placed, each in a chip-box, with two 

 or three dead leaves, whilst the remaining subject was confined to a 

 roomy cardboard box, which was absolutely bare. Of those in the 

 chip-boxes with dead leaves, both behaved alike in spinning to the 

 underside of the leaves supplied. That in the bare box went to the 

 top and pupated without any attachment, except the anal pad, and 

 this was so insufficient that, upon moving the box, the pupa fell to 

 the bottom. My object, however, was to satisfy myself whether 

 R. betulae really ' went to earth,' and the six larvae which were left 

 on their foodplant with earth to take to if they chose, and this earth 

 covered with dead leaves, moss, etc., so as to imitate their natural 

 surroundings, gave an unanimous reply that R. betulae does not go 

 beneath the surface of the ground. All spun up between leaves, moss, 

 etc. I have pretty regularly each year taken a number of R. betulae 

 larvae by beating the foodplant (blackthorn), and, although I must 

 admit that, as the breeding of them has occurred during the rush of 

 1 work,' I have never made careful notes, yet I am positive that 

 never, in my experience, has a larva pupated beneath the surface 

 of the earth, although there has always, in the breeding-chambers, 

 been a layer of soil." The observations of such capable observers 

 as these must be considered as most conclusive, and sufficient to dispose 

 of the statement that the larvae have been observed to suspend them- 

 selves by silken pad and girth in the orthodox fashion of Strymon 

 pruni and Edwardsia w-album. They also go to prove that their 

 pupation-habit is certainly not identical with, nor, indeed, so very 

 similar to, that of Bithys quercus. [See also Chapman, antea, p. 229, 

 on the cremastral structure of the pupa of Ruralis betulae.] 



Maturation of pupal colours. — A larva that had been in the 

 quiescent stage preceding pupation for at least three days, pupated on 



