The Nest-building Odynerus 



domen is paralysed. The insect no longer 

 uses its anal lever when walking. The legs 

 are perfectly mobile and the grub employs 

 them : it crawls, it drags itself along, pro- 

 gressing with a vigour which would be nor- 

 mal but for the obstruction of the hind- 

 quarters. The head also moves; the 

 mouth-parts snap as usual. Apart from the 

 paralysis of the abdomen and the mutilation 

 of the rectum, the victim is in every respect 

 the same as the lusty larva, browsing peace- 

 fully on the poplar-leaf. We have here a 

 magnificent demonstration of the principle 

 before which certain peevish objections are 

 bound to fall to the ground : the effect of the 

 sting is not felt, at least not at first, except 

 at the points attacked. The sting strikes 

 the nerve-centres of the abdomen and the 

 abdomen is paralysed; it spares the thorax 

 and the legs and head both remain active. 

 Ten hours after the operation, I examine 

 the grubs again. The hind-legs are tremu- 

 lous and are no longer of use for locomo- 

 tion. Paralysis is overtaking them. Next 

 day, they are inert; so are the middle legs. 

 The head and the fore-legs are still work- 

 ing. On the day after, the whole grub is 

 motionless, except the head. Lastly, on 

 the fourth day, the creature is dead, really 

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