488 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 1925 



Doctor Chapman noted that the life history is interesting as being 

 parallel to, though differing from, that of L. arion. The 3^oimg larva 

 feeds in the autumn in the flowers and other portions of Gentiana 

 fneumoncbnthe^ and probably of other gentians. So far it is exactly 

 parallel in growth to other blues, such as many of the English 

 plebeiids that pass the winter in the third instar. When it reaches 

 the third instar it leaves the plant, wanders off, and hitherto efforts 

 to carry it further have failed. At this point it agrees with L. arion 

 in habits, but it is not like L, avion., which is in a remarkably modified 

 and concentrated (as regards skin armature) fourth instar, but is 

 in quite an ordinary third instar. In its plant life it has differed 

 also in that several, often five or six, larvae live amicably together 

 in one flower, whereas L. arion is solitary, and if by accident two 

 larva} meet, as by a second egg having been laid on the same flower 

 head, or especially when incautiously associated in captivity, they are 

 inveterate cannibals. 



The remaining history is that both L. arion and L. alcon live in 

 the nests of ants — Doctor Chapman kept both species in those of 

 Myrniica scahrinodis — and pupate in the nest. The differences are 

 that L. arion eats the ant brood, whereas L. alcon certainly sucks 

 their juices without eating them; and Doctor Chapman could not 

 prove that it ever actually ate them, though he thought it did so 

 W'hen past the winter when its food would more often be ant pupa3. 



L. avion is in its fourth instar and is provided with a skin arma- 

 ture not unsuitable to it wdien fully grown. L. alcon has only a 

 third instar armature, and when full grown might be almost de- 

 scribed as without one for, like L. avion., it does not molt after en- 

 tering the ants' nest, but attains its full growth still in the third 

 instar. The skin is then so attentuated that the fat masses are very 

 obvious, and its general aspect is like that of an internal feeder 

 rather than that of a butterfly. Doctor Chapman remarks that it is to 

 be noted as exceedingly remarkable that a butterfly larva should 

 attain its full growth after only two molts. 



M. Oberthiir, who is familiar with localities where L. alcon is 

 common, considered it highly probable that it had a life history 

 similar to that of L. avion., and with the assistance of Mr. Harold 

 Powell, found that ants would carry off the larvae of this butterfly, 

 and also that the larvae would lap up the juices of wounded ant 

 larvae. He provided Doctor Chapman with the young larvae used 

 for observation both in 1916 and in 1917, and his success in rearing 

 the insect was, he says, entirely due to M. Oberthiir's initiative. 



Mr. Powell saw the larvae of L. alcon carried off by Tetva/morum 

 C(psj)itu7ii and by Tajnnonia evraticuni. Acting on this hint Mr. 

 Donisthorpe pro\'ided himself with a nest of Tetramorvm., and now 



