78 MISS K. HADDON ON TJIE 



The habits of these larvae have already been described by 

 Newport * and later writers, but their accounts do not entirely 

 agree. Newport describes the bite of the larva as causing great 

 pain to the snails on which they feed ; whereas Fabre f, in a 

 popular article on the subject, says that the snail is anaesthetised 

 by the bite. It may be of interest, therefore, to record my own 

 observations, which were carried out with a Zeiss binocular, the 

 larvae being placed with some moss in a shallow glass dish and 

 supplied with small snails. 



The larvae crawl about, feeling their way with their maxillary 

 palps, which are kept constantly in motion, the head being fully 

 extended, so that the whole of it protrudes beyond the prothorax ; 

 whereas when the animal is at rest only the mouth-parts are 

 visible. The snail apparently is found quite by chance, and if 

 hungry the larva at once fastens on its prey. The mandibles are 

 worked laterally, and bending its head down it cuts its way into 

 the snail, which promptly withdraws into its shell, the larva 

 following. If left undisturbed the larva feeds continuously, and 

 is frequently joined by others, until the snail is finished ; but if 

 it is pulled off at once, the snail pursues its way apparently un- 

 injured. Wishing to see more clearly the method of procedure, 

 I supplied small slugs as food instead of snails, so that there could 

 be no retreat into a shell. The larva bit the slug on the visceral 

 hump, but apparently could not get a sufficient hold, as the slug 

 with a twist of its body slipped away leaving a mass of mucus over 

 the head of its enemy. The larva at once desisted from its attack 

 and tried to free itself from the slime by working its jaws and 

 rubbing them with its front legs. These methods failing, it 

 curled up and cleaned itself with the adhesive organs in the 

 terminal portion of its abdomen, repeating the process long after 

 there were any signs of slime on the head, probably to cleanse the 

 hairy bases of the mouth-parts. 



In the next attempt to feed the larvae with slugs the attack was 

 more fortunate, the larva striking right into the pulmonary cavity 

 of its victim ; but either the food was not to its taste or else it 

 was not hungry, as it shortly let go, and the slug, which had 

 previously been lethargic, glided off apparently undisturbed. 



These observations show that — in these cases, at any rate — 

 there was no anaesthetising. 



When feeding, the larvae keep their jaws constantly moving, 

 and thus their mouth is bathed in the juices from the snail. 

 Newport J also observed some dark-coloured liquid, which flowed 

 from the mouth of the larva at the time of its attack and appar- 

 ently acted as a poison, for the snail was much more affected by 

 the bite of a larva than by a mechanical injury, such as piercing 

 with a needle. He apparently failed to notice that the mandibles 



* G. Newport, "On the Natural History of the Glow-worm," Journal of the 

 Proc. of the Linnean Society, Zoology, vol. i. 1857, p. 40. 

 t Fabre, " The Glow-worm," Century Magazine, November 1913. 

 X Loc. cit. p. 58. 



