Dec. 1, 1869.] 



HARDWICKE'S SCIENCE-GOSSIP. 



273 



INFLUENCE OE FOOD AND LIGHT ON 

 LEPIDOPTERA. 



T PROCURED about 2,500 larva? of the Tiger 

 -*- Moth, in a young state. I divided them into six 

 lots, keeping each in a separate cage, and feeding 

 them differently. One lot was fed on willow, another 

 on butter-bur (Petasites vulgaris), another on haw- 

 thorn, another on plum, one on dock, and one on 

 nettle, grass, bramble, and various other kinds of 

 food. A considerable proportion of each became 

 perfect insects, and I could detect no difference 

 whatever in the colours, from the food they had 

 lived upon. That is to say, the variations in colour 

 and marking, were not to be traced in any case to 

 the food. I kept several batches of eggs, and 

 reared the larvae carefully through the winter, and 

 then again divided them, giving each lot a different 

 kind of food. Again the same result. I found that 

 one year the larva? I had brought from the coast 

 had usually the inferior wings more or less of a 

 yellow shade, instead of the bright scarlet of the 

 Cheshire specimens. 



Having for many years continued these experi- 

 ments without obtaining any marked results, I this 

 year tried another of a different nature. I selected 

 the tortoiseshell butterfly, as one of the least variable 

 species we have, and I procured several broods of 

 young larva? just emerged from the egg. These I 

 kept in a dark box until I had all ready, and then I 

 divided each brood into three lots, putting one-third 

 into a box in my photographic room which is lighted 

 with orange-coloured glass, one-third into a box 

 lighted with blue glass, and the ventilators care- 

 fully shaded so that only light of a blue colour could 

 reach the larva?, the remainder were put into an 

 ordinary cage, in the natural light. 



The latter fed up and came out into butterflies in 

 the usual time. Those in the blue light were not 

 healthy, and though every care was taken, at least 

 fifty or sixty died before changing, and a consider- 

 able number changed into chrysalides, and then 

 died ; those that came out into perfect insects were 

 very much smaller, than usual. Those lighted by 

 orange-coloured glass fed up very well, but many of 

 the two first lots had come out before one of them 

 changed into chrysalis ; scarcely one of them died, 

 and I examined each one before I allowed it to fly, 

 to see what effect had been produced. 



Those reared in the blue light differ from the 

 ordinary form in being on an average much smaller ; 

 the orange-brown is lighter in shade, and the yellow 

 and orange run into each other, instead of .being 

 distinct and separate. 



Those reared in the non-actinic, or yellow light, 

 are also smaller, the orange-brown is replaced by a 

 salmon colour, the venation more strongly marked, 

 and the blue dashes at the edge of the wings 



in the usual form] are in these of a dull slaty 

 colour. 



One evening I found about six hundred butter- 

 flies out of chrysalis, of those in the photographic 

 room, and taking each one carefully I examined 

 them all and allowed them to fly ; shortly afterwards 

 I found the whole of them had settled against the 

 wall of the house, and presented a most remarkable 

 appearance : they remained there more than half an 

 hour. The western sun was shining against the wall, 

 and it is not unlikely that when suddenly brought 

 from the red light, where they had spent all their 

 lives, to the bright daylight, they were so daz- 

 zled as to act in this peculiar manner. 



The results of this experiment do not show any 

 very startling change in colour, such as one would 

 have expected from the known effects of light on 

 plants, and from the occasional occurrence of very 

 much more strange varieties one now and then 

 meets with, which cannot have been subject to such 

 severe treatment ; still, when we consider that even 

 this difference is caused in one generation, and in 

 the course of a month, it is a very suggestive fact, 

 and leads one to think that light has certainly as 

 much or more effect on the colours of Lepidoptera, 

 than the difference of food, and might in a long 

 series of generations lead to very material changes 

 in both form and colour, and perhaps considerably 

 modify our ideas of what constitutes a species. 



J. SlDEBOTHAM. 



Remarkable Flight oe Moths and Butter- 

 flies. — A lady who lives near Conway wrote to me 

 a few weeks ago in the following words: "On 

 Saturday, the 2nd of October, we noticed a great 

 rise in the barometer, and the air out of doors was 

 warmer than in the house, and at one o'clock, all 

 my family turned out to see ' the wonderful sight,' 

 viz., & flock of Humming-bird Hawkmoths, and a 

 great many butterflies of the Vanessa iirticce, and 

 still more of Vanessa atalanta. On one plant of 

 mesembryanthemum I counted four of Atalanta and 

 two Urtica, and from one place as I stood still I 

 counted forty of the moths. Is this the usual time 

 for these animals to flourish ? And is it uncommon 

 to see them in such great numbers?" I am no 

 entomologist, so I could only tell my correspondent 

 that all the three kinds are seen in autumn, and 

 that I believed the Humming-bird Moth to be an 

 insect sufficiently rare to render such a sight as she 

 described very remarkable. Can any reader of 

 Science-Gossip give any further information, and 

 say whether large flocks of these insects made their 

 appearance elsewhere ? From the sudden rise in 

 the temperature, I should suppose that the wind 

 brought them from some warmer place where they 

 are more plentiful. — Robert Holland, Mobberley, 

 Cheshire. 



