322 THE ENTOMOLOGIST. 



it on to the earth.* There they proceed to hide themselves 

 behind any suitable pieces of vegetajbion that they can find, 

 their object being apparently to avoid the light. In the absence 

 of hiding places they simply wander about aimlessly. In the 

 night it is presumed the larvae search for food ; but it is esta- 

 blished that at this point they have lost their cannibal habits. t 

 The principal object of the experiments which are about to be 

 described was to discover the natural food of the larvae after they 

 drop off the thyme plants, and here two clues leading in 

 apparently opposite directions present themselves. 



In the first place, the fact that the adult female deposits its 

 eggs on plants growing on or near ants' nests, coupled with the 

 well-known fact that ants are in the habit of milking the larvae 

 of many Lycaenidae, suggested that the larvae of avion might be 

 fed by ants or find food in their nests. 1 This theory is sup- 

 ported by the discovery in Cornwall barely below the surface of 

 the soil on the top of an ants' nest of three full-fed larvae 1 

 accompanied by one of smaller size — a discovery which definitely 

 established the fact tbat the insect hibernates as a larva — but, 

 as no more could be found in a large number of nests which 

 were examined, the discovery in question may have been due to 

 an accidental coincidence. There seems to be no reason to 

 doubt that the larvae referred to had entered the soil for the 

 purpose of pupation, the discovery of two pupae § in close 

 proximity to one another by Mr. A. L. Eayward and the author 

 having made it clear that more than one larva may select the 

 same spot for this purpose. 



The other theory is suggested by the fact that the larvae after 

 the third moult eat honey and bore into green peas,i on which 

 food they can subsist for several weeks. 



Much discussion has taken place since the publication of the 

 author's previous articles in connection with the two theories 

 which have been briefly mentioned, there being a sharp division 

 of opinion among entomologists. Dr. Chapman (whose know- 

 ledge of the earlier stages of European Lepidoptera is probably 

 unrivalled) and those with him are convinced that the larva of 

 arion lives within the nests of the ants after its third moult. In 

 opposition to this view it is urged that the eggs may be deposited 

 on the ants' nests only in order that the larvae may be protected 

 from their natural enemies by the presence of the ants, which 

 milk them ; and also that, if the larvae were ever really in the 

 nests, they must have been found in the course of many thorough 

 searches by the author and others. As to these searches it must 

 of course be admitted that, as only a few eggs are deposited on 

 each nest and the larvae are so small and in colour resemble the 

 soil so closely in September when some of the searches were 



* ' Entomologist,' xxxii. pp. 104-106. f Ibid, xxxvi, pp. 57-60. 



I Ibid, xxxix. pp. 145-47. § Ibid, xxxviii. pp. 193-94. 



