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XI. What the larva of Lycaena arion does during its last 

 instar. By T. A. Chapman, M.D., F.Z.S. 



[Read June 2nd, 1915.] 



Plates XXXVIII— XLVI. 



For many years the life-history of Lycaena arion has 

 been a puzzle, and has much interested and exercised 

 those of us who find the habits of butterflies, and especially 

 of British butterflies in their earlier stages, to present 

 absorbing biological matter worthy of our best attention. 



I am absolved from traversing the whole ground, ah 

 initio, by the valuable resume of all that was known up 

 to last year, and references to where the recorded facts 

 may be found, that was given us by the Rev. Geo. Wheeler 

 in Tutt's " British Lepidoptera," vol. xi. p. 331 et seq. 



It may be desirable, however, so far to recapitulate 

 as may make it clear in what the puzzle and mystery 

 consisted. 



The majority of European Blue butterflies hibernate 

 as larvae in their third instar, having in all five instars. 

 Others hibernate as full-grown and full-fed larvae ; others 

 as pupae, and some as eggs. Each of these different 

 habits of, or rather stages for, hibernation is adopted by 

 more than one species. 



L. arion differs from all these, and agrees with no other 

 species in its method of passing the winter. 



It is not, I believe, alone in having only four larval 

 instars, but to have five is, one may say, the rule in these 

 butterflies. 



Living on thyme, chiefly the flowers, it at length reaches 

 the fourth, which is its last, instar some time in or about 

 August, and then goes into hibernation. When it does 

 so, it is so small that until Mr. Frohawk (Entom., vol. 

 xxxix. p. 145) showed that it was still in the same instar 

 when full grown in the spring, one could not avoid sup- 

 posing that it would have at least one more moult in the 

 spring, and that probably one had made some error in 



TRANS. ENT. SOC. LOND. 1915. — PARTS III, IV. (JUNE) 



