ARICIA MEDON. 277 



Harrison in a passage which it is worth while to quote in full. He 

 observes (Ent. Rec, xviii., p. 247) A. medon " and its aberrations 

 were very abundant this year [1906] , in all its known haunts. I 

 should think its numbers were about six times that of a normal year. 

 This is the more extraordinary, as a friend and myself went for larvae 

 at the end of April, and, except for a single larva I obtained, not one 

 was visible. In an ordinary season between two and three dozen 

 larvae has been the usual take. What was still more remarkable was 

 the absence of any indication of the larvae feeding. My friend Mr. 

 Johnson, of Gateshead, also made a search, and also with a total catch 

 of one. I fancy the larvae fed up very early in the spring, or took 

 advantage of the open winter and fed up then. Or, perhaps, with the 

 hereditary tendency to double-broodedness, the larvae fed up last year 

 in the warm autumn we had, and remained as pupae all the time. A 

 slight confirmation of one or other of these surmises I see in the fact 

 that, in spite of the cold June, the insect was out about ten days 

 earlier this year than in 1904." 



Chapman, on the contrary, writes (in I'M.) as follows : — 



" I obtained eggs of this species in June, and took some young 

 larvae with me to Switzerland on July 1st. Several died, but I brought 

 home with me six larvae apparently in 4th skin (one beyond hibernating 

 stage) on August 17th. A few days later they all died. I found at 

 home a plant on which I had left a few eggs. It was placed out of 

 doors on the south side of the house, under a sleeve of thin net, that 

 was intact. There was no sign of larvae having fed up or emerged, 

 but many traces of the feeding of young larvae, and there I find to-day 

 (September 5th, 1908) two specimens, under leaves, very small, 

 apparently thinking of hibernating." And again : — " Eggs laid in 

 June, some larvae taken through July to Switzerland and brought 

 home in August, then died, apparently waiting to hibernate and being 

 interfered with in that desire and unable to go forwards. Other eggs 

 were left on a plant at Reigate, in mid August several small larvae 

 were on the plant and were quiescent, no sign of any larvae feeding up 

 or having fed up. 



On December 1st, a larva about 8*5mm. long was seen and 

 disturbed, and hung by a thread, and was quiet motionless as if dead so 

 long as watched. December 2nd. The larva has crawled up and is 

 resting on a small half-dead leaf. 



Both these lots ought to have produced summer imagines in 

 August. I fancied my Swiss ones failed by being taken to Saa Fee 

 and Zermatt, where the temperature (except in the sun. which was not 

 allowed them) was too low for them to progress. Still, I think when 

 they died they were beyond hibernating stage, and had all gone well 

 with them, they would have emerged this year. Their deaths may be 

 attributed to their unsatisfactory treatment. Those, however, in the pot 

 at home, clearly are acting as examples of a single-brooded race would 

 do. The whole experience shows the English medon to have a strong- 

 tendency to be single-brooded (Chapman). 



The question whether the single or double-brooded habit is 

 ancestral of course depends on the original home of the species, 

 that is, whether it is one which has spread from high latitudes (or 

 altitudes) to lower ones, or vice versa. Grum-Grshimailo advances 



