MODES OF EMERGING FROM PUP^. 327 



and forwards, and shifting their hold till she was 

 entirely extricated, when they left her to recover her 

 strength by herself. " Probably," say our authors, 

 " the extreme length of the two pair of l>ind-legs of 

 these animals may render such assistance necessary 

 for their extrication."* We, however, imagine 

 that Captain Percy's instance was accidental and 

 anomalous ; for the insect having already extricated 

 her head, shoulders, and fore-legs, all the difficulties 

 were surmounted. From the insect being so very 

 common, also, the circumstance of such assistance, 

 if it did happen, must be a matter of frequent ob- 

 servation ; but we have witnessed a considerable 

 number of several species of this family undergo the 

 change without any assistance whatever. f 



The best ascertained case of assistance occurs 

 among ants, and was first observed by the accurate 

 Swedish naturalist De Geer, though the best ac- 

 count of it is given by the younger Huber. " The 

 greater part of the pupae," says he, " are enclosed in 

 a tissue spun by themselves before their change ; 

 but they cannot, like other insects, liberate themselves 

 fi-om this covering by effecting an opening in it with 

 their teeth. They have scarcely the power of mov- 

 ing ; their covering is of too compact a texture, and 

 formed of too strong a silk, to allow of their tearing 

 it without the assistance of the workers. But how do 

 these indefatigable attendants ascertain the proper 

 moment for this process? If they possessed the fa- 

 culty of hearing, we might imagine they knew the fit 

 time, from some noise produced in the interior of the 

 prison by the insects whose development has com- 

 menced ; but there is no indication favouring this 

 opinion ; it is probable they have a knowledge of it 

 from some slight movements that take place within, 

 which they ascertain through the medium of their 



* Intr. iii. 2^« f J. R. 



u 2 



