ON ORGYIA AUROLIMBATA, GN., AT BEJARi 113 



On Orgyia aiirolimbata, Gn., at Bejar {trlth jdates). 



15y T. A. CHAPMAN, M.D., F.Z.S., F.E.S. 



Last year (1901) I was fortunate enough to meet with Oriiijia ilithia 

 var. splcndidK and to observe its remarlvable habits, especially in the 

 matter of pairing and egg-laying. (See Eut, Record, vol. xiv., p. 41.) 

 This year (1902) no trace of U. spleudida was seen, but the not very 

 distantly related (>. aiiroliinhata was fairly common in the larval state, 

 and enabled me to make some observations on its structure and habits. 

 These seemed to me to be of great interest by comparison ^^■ith those 

 of (K spleudida, both in the points in which they were similar and in 

 those in which they ditiered. 



The larvse were especially attached to broom, and were met with, I 

 think, on all the species we noticed of that genus, and, occasionally, on 

 some other plants, but more rarely, yet sufficiently often to lead me 

 to suppose that it is attached to broom, but is also in some degree 

 omnivorous. We met with it everywhere in the vicinity of Bejar 

 where broom grew, and also at Piedrahita, where, however, it was less 

 common, probably because most of them had then spun up, since it 

 was here (July 20th) that the only imago seen was met with. About 

 this time several of the cocoons I had, appeared to contain mature 

 females, but the only attempt at sembling that I made was fruitless. 



I gave several opportunities of pairing to b'-ed specimens, but 

 always without result, probably because the female cocoons I had were 

 not at the right stage, and I only bred four or five females altogether, 

 the difficulties of rearing larvse when without proper facilities for so 

 doing being very great. I have a suspicion, however, that some of 

 these specimens did pair, and that, when the males were within the 

 female cocoons, I was unaware of their emergence, since the males 

 seemed more worn than their apparent dates of emergence warranted, 

 and some of the eggs seem fertile that otherwise should not have 

 been. 



It was not till the day after my return home ('■/;., August 1st) that I 

 found a S moth emerged that at once paired when offered a ? cocoon. 

 His procedure was very different from that of the J (>. spleudida. In that 

 species, the male carefully examines all that part of the cocoon of the 

 female that is exposed until he finally settles down, with his head at 

 the emergence end of the cocoon ; here he rests quietly for some 

 minutes, whilst, no doubt, the female is making an opening in the 

 cocoon. He then enters through this opening. The <? of the insect we 

 are now considering made no such search, but seemed satisfied with 

 the first portion of the female cocoon that he came to, and at once 

 commenced actively to make an opening for himself, through which 

 he entered. This was at about 10 a.m., he was still Avithin the 

 cocoon late in the evening, but had emerged the following morning. 



This cardinal difference of the opening in the female cocoon, being 

 made in the case of (>. sjdejidida by the female, and in the case of (>. 

 auniliiidiata by the male, is associated with several other differences 

 of habits and some corresponding ones of structure. 



The first point that one observes is that the male was seen to tear 

 the opening in the cocoon by means of a very definite short-hooked 

 spine at the dorsal margin of the apex of the first tibia. Having, as 

 a fulcrum, the front of the head and antennal bases pressed against 



May 15th, 1903. 



