8 



species to complete their metamorphoses, possibly being a means of 

 securing the species against extermination in case of circumstances 

 prejudicial to rapid development occurring. In other words, although 

 the species is practically double-brooded in the south, it still retains 

 a disposition to single -broodedness, which may, under certain 

 conditions, become generally effective. 



I have already referred to the food of the larvK, and on a former 

 occasion I expressed the opinion that although tamarisk {Tama?-L\ 

 anglica) grew so profusely all along the slopes on which the insect 

 occurs, I could not think that that plant had anything to do with 

 the prevalence of the insect in that particular part, further than 

 affording good cover. One of my chief reasons for this was the fact 

 that, although I had looked over the tamarisk bushes again and 

 again, I had failed to find any signs that appeared to show that they 

 had been eaten by any lepidopterous larva. However, on the 

 occasion of my last visit to the locality, I happened to be returning 

 along the banks early one evening, and, noticing the tops of several 

 shoots to be very much eaten, I stopped to examine the cause, and 

 was surprised to find a number of larvae of Hadena okracea feeding 

 greedily upon them, thus showing that all lepidoptera are not abso- 

 lutely averse to the plant. Possibly, then, the luxuriant growth of 

 tamarisk may, after all, have something to do with the abundance 

 of A. viarginipiinctaia at the particular place, and I hope, should I 

 have any luck with the larvae I now have hybernating, that I may 

 yet have a chance of deciding the question.* 



Yet one other point of interest came under my notice on the 

 occasion of my last visit. 



There can be no doubt that a mottled-grey insect resting on the 

 rough surface of a more or less grey stone is fairly well protected 

 from observation ; but if that same grey insect rests upon a dark 

 green ivy leaf one would naturally conclude that it would become a 

 conspicuous object. It is quite true that a moth so placed would 

 receive the full benefit of the direct sun heat, if that be of importance 

 to it, equally with those moths resting on the stones ; but so far as 

 protection from observation it would clearly be at a disadvantage. 

 The ivy plants have grown very considerably of late years, and in 

 many parts cover up the stones, yet it is rarely I have found moths 

 resting on the leaves ; when, however, I have so found them, they 

 have been just as frequent on the leaves as on the stones. It 

 appeared to be a point that needed explanation, and the explanation 

 that presented itself appeared to me to be a simple one. I can, 

 perhaps, best convey it by describing the circumstance that brought 

 it to my mind. 



As already stated, I arrived at Eastbourne on the afternoon of 



* Since this was written tamarisk was given to some nearly full-grown larvae, 

 but they not only refused to eat it, but appeared to avoid it even as a resting- 

 place. 



