Nov. 1, 1863.] 



HARDWICKE'S SCIENCE-GOSSIP. 



m 



THE PUPA OP A DRAGON-PLY. 



ON the 5th of December, 1867, I procured from 

 a Loudon shop the pupa of a Dragon-fly, 

 which was either JEshna varia or JEshna grandis, 

 and seeing it stated in the October number of 

 Science-Gossip that " little is known of the habits 

 of larvae and pupa? of the Dragon-fly, and any one 

 who could describe them would do good service to 

 science," I determined to watch this pupa carefully, 

 and placing it for that purpose in a large-mouthed 

 water-bottle, I thrust a long piece of lath into the 

 bottle, for the pupa to hold on by. To this lath the 

 creature would cling for hours, quite motionless, 

 with its head downwards, and with the horny ap- 

 pendages at the end of its abdomen just touching 

 the surface of the water. 



If I approached too closely when it was at the 

 near side of the lath, it would nimbly slip round to 

 the far side, in order to escape observation, but ap- 

 parently without being much alarmed. At other 

 times its movements were rather slow and deliberate. 

 It would rarely leave its resting-place, unless at- 

 tracted away by the movement of some small 

 creature suitable for its food. But when the water 

 was changed and the bottle cleaned, and pupa and 

 lath were both taken out together, — on being put 

 back, it would swim about, allowing its legs to hang 

 loosely by its side, and propelling itself along by 

 squirting water out of its abdomen ; but it soon 

 tired of the exertion, and returned to the lath. 



The apparatus with which it is provided for seiz- 

 ing its prey is so remarkable, that although it has 

 been described before, I cannot refrain from touch- 

 ing briefly upon it here. 



Speaking very roughly, this apparatus may be 

 said to consist of a kind of flattened arm, which, 

 when not in use, is tightly folded up (like a car- 

 penter's rule) under the creature's body; it consists 

 of two joints, and instead of being fixed to the 

 shoulder, as in man, it is attached to the under part 

 of the pupa's head, to the part— if the comparison 

 is admissible — which in us, is between the throat 

 and the chin. The first joint of this arm (or pre- 

 hensile apparatus, as it is called) folds back under 

 the thorax ; the second joint folds forwards, and is 

 just sufficiently long to reach to the mouth. Its 

 extremity is furnished with two hooks or claws, 

 which open out laterally, somewhat as the little 

 finger and thumb would do when our hand is held 

 palm uppermost and widely spread out. These 

 two claws are long enough to cross each other, and 

 by so doing they partially cover and conceal the 

 mouth of the pupa when the creature is at rest ; 

 and hence the apparatus has received the name of a 

 " mask." 



The length of this mask bears about the same 

 proportion to the length of the pupa, that the 

 human arm bears to our height. It appears to 



have little or no lateral play, but can only open out 

 and act straight in front of the head of the pupa. 



When the creature spies anything worth eating, 

 which is moving about in the water or on its sur- 

 face, it creeps up to the object, until it is within 

 striking distance, and then suddenly darting out its 

 mask, and opening the claws at the end, it seizes 

 the prey : the mask is then drawn back, so as to 

 present, in the most convenient manner, the food to 

 the mouth of the pupa, until the prey is entirely 

 devoured. 



The Dragon-fly has been loosely accused of extra- 

 ordinary pugnacity in all stages of its existence ; but 

 as far as the larva and pupa are concerned, I could 

 see no symptoms of such a propensity. On the 

 contrary, the creature in both those stages was 

 rather timid, and would get out of the way of such 

 things as the water-scorpion ; and taking into con- 

 sideration the fact of its turning round so slowly, 

 and of its having scarcely any means of defending 

 itself against a nimble foe at close quarters, it is by 

 no means suited to promiscuous fighting ; and I 

 believe never seizes anything, except in obedience 

 to the dictates of hunger. 



I had great difficulty in procuring food for the 

 pupa in the middle of the winter, and owing to this, 

 the only thing it had to eat from the 6th of Decem- 

 ber till the 13th of the following February — a period 

 of seventy days — was a common house-fly. 



After the 13th of February, and at intervals vary- 

 ing from three to ten days, according to what could 

 be obtained for it, it ate ladybirds, blue-bottle flies, 

 water-boatmen (of which it was especially fond), a 

 tadpole or two, and several small red worms. 



It refused water-beetles of all sorts, and with one 

 exception — if it can be called an exception — it never 

 took any notice of things which were dead or did 

 not move. One day, however, I observed that (in 

 a glass globe standing in my room) a water-boatman 

 (Notonecta) had fastened upon a small eel about 3i 

 inches long, had killed it, and had begun to eat it. 

 I placed them both, without disturbing the Notonecta, 

 into the pupa's bottle. The pupa seeing the water- 

 boatman move, took a shot at it, but striking the 

 eel instead, quietly devoured the whole of the latter 

 up. 



On another occasion I saw a water-scorpion {Nepa 

 cinerea) take away from the pupa, a Notonecta which 

 the pupa had begun to eat ; but this was only two 

 days after the feat of despatching the eel, which was 

 nearly twice its (the pupa's) length. 



I have said that the pupa generally avoided the 

 water-scorpion. Once, however, when the former 

 had had nothing to eat (except a ladybird) for some 

 twenty days, it seized a Nepa cinerea by the abdo- 

 men. The Nepa at the same time attacked the pupa 

 with its sharp fore-legs, evidently much to the dis- 

 comfort of the former ; and the only way in which 

 the pupa appeared to be able to get rid of the 



