VARIATION. 155 



females are on the wing ovipositing, etc., and we get no real idea of 

 how much their wings are used. Whoever captured a <? Bombyx 

 qiierciis on the wing late at night? I have taken dozens of females in 

 this way. But Mr. Arkle leaves out of sight the probable reason of the 

 larger wing area generally found in female moths where both sexes are 

 active. I refer to the extra weight of the body when distended with 

 ova which the females have to carry. The examples quoted by Mr. 

 Arkle might be increased tenfold, and as a rule the greater the 

 difference in the weight of the body in the sexes, the greater the 

 difference in the wing area. Lasiocampa quercifolia is a case in point. 

 Where the bodies of males and females are almost of equal weight, the 

 wing area is much the same. This would more than counteract 

 " the greater use in the males " if there be such greater use, which I 

 much doubt. — Ed.] 



^^ARIATION. 



Varieties of Zvg^na filipendul^e and Z. trifolii. — Whilst 

 collecting in the Isle of Wight, this year, my wife found on some 

 undercliff a colony of Z. filipendiilce^ and amongst them the yellow 

 variety. We visited the spot on several occasions after this and were 

 fortunate enough to find two more specimens of this variety, all of 

 them without the faintest tinge of red in the yellow ; although we 

 examined hundreds of this species we failed to find any other varia- 

 tion. I also found in a damp meadow Z. trifolii abundantly, the 

 type of which was scarce ; the majority had the two spots in the centre 

 of the wing coalesced, and in many, the five spots were joined and 

 formed a brilliant splash. In both species I noticed that the larv^ had 

 spun up in an apparently haphazard way, choosing whatever object 

 came first, such as stems of various plants and thistle leaves, and many on 

 an adjacent boathouse. — P. W. Abbott, Birmingham. August, 1891. 



With further reference to the occasional occurrence of the yellow form 

 oi Z, filipendulce, I was fortunate enough to find one myself on July 20th 

 in the same locality referred to by Mr. Abbott in the preceding note, viz., 

 a rough grassy undercliff, near Brook, in the Isle of Wight. The species 

 was excessively abundant, and the few thistles scattered throughout the 

 undercliff were simply a mass of " Burnets," and whilst in some spots 

 it was difficult to find a suitable grass stem without a cocoon attached, 

 yet these were not confined to the grass stems, as many dozens were 

 spun up on the boathouse Mr. Abbott mentions, and others on a small 

 windlass close by. In one case a second cocoon was made almost over 

 the first on a grass stem, but not enough so to interfere with the proper 

 emergence of the imago ; whilst in the case of Z. trifolii, in another 

 locality, the cocoons were distributed in quite as erratic a manner. I 

 found several on large rush stems, and one on the under side of a broad 

 leaf of Iris. With reference to Z. filipetidulcs, I may say that, although 

 I have worked the same spot for several seasons, I have never seen the 

 species in anything approaching similar abundance, nor have I met 

 with the yellow variety before, of which, unless my memory deceives 

 me, Mr. and Mrs. Abbott secured four specimens, one of which they 

 very generously added to my collection. They also succeeded in 



