442 NATURAL SCIENCE. June, 



cons'ders (Trans. Ent. Soc. Lond., 1892, pt. iv.) this species to be 

 less susceptible than other CatocaUdae. 



Catocala fraxiiii certainly showed a distinct diiTerence, not only 

 of shade, but of colour, larvae reared in green surroundings being 

 distinctly greenish in hue, while those in dark were brownish. Mr. 

 Poulton ol)tained only a difference in shade, otherwise his results 

 were similar. 



With Mamestra bvassica I had negative results ; the larvae were not 

 affected at all by surroundings, and I believe this unsusceptibility to be 

 due to the burying habits of this species, which render colour of 

 secondary importance to the larvae. Mr. Poulton's results differed a 

 little from mine, but he thought that his larvae were not in such a 

 healthy condition as mine, which might account for this. There are, 

 however, special difficulties in investigating M. brassico', and Mr. 

 Poulton considers the experiment worth repeating. 



Since publishing these results, I made some experiments, at Mr. 

 Poulton's suggestion, on larvae of Triphena pronuba, which I was rearing 

 for him for other purposes. I had 59 larvae in different surroundings, 

 and as this species, like M. brassier, buries by day, I used different- 

 coloured materials on the floor of the cylinder, such as white sand, 

 yellow gravel, pounded red flower-pot, and, in one case, small coal. 

 The larvae buried in all these, except in the coal, which they evidently 

 disliked, but the results were, as in M. brassica, negative, with two 

 possible exceptions from green surroundings, without any burying 

 materials ; these were, however, not very definite. The burying 

 materials were in all cases used in addition to sticks of the suitable 

 colour mixed with the food-plant. 



Besides the foregoing experiments, I also made some notes on 

 the red spots in Smerinithiis larvae, from larvae of S. tilia sent me by 

 Mr. Perkins at Mr. Poulton's request. These larvae were all from 

 parents which had been spotted in the larval stage. Unfortunately, 

 many were injured by their transit by post, and I only succeeded in 

 rearing four, which were all spotted. I also captured a larva of 

 5. poptili in which the spots were extremely well marked. The spots 

 were certainly protective in effect, on account of their resem- 

 blance to the dark spots or blotches common on leaves of poplar, 

 and this fact was long ago pointed out by Mr. Peter Cameron 

 [Trans. Ent. Soc. Lond., 1880) ; but although he considered the like- 

 ness to galls (Phytoptus) very striking, it teems to me, in S. populi at 

 any rate, far greater to flat spots on the leaf seen with the light shining 

 through them. 



In S. tilia: I studied the development of the spots very carefully, 

 and in one individual I found them very linear and strongly sugges- 

 tive of coloured borders ; in the others they were much bolder and 

 rounder, and presented quite a different appearance. Professor 

 Weismann, as is well-known, considers the spots as on the way to 

 develop into borders, while Mr. Poulton takes the view that we 



