HISTORY OF INSECTS. 15 



single meal : not only is its pace slow, but it can walk in 

 no other direction than backwards ; its grim aspect, com- 

 bined with this awkwardness in progression, appears to offer 

 insuperable obstacles to the capture of its prey. 



The first step of the larva is to trace in the sand a circle, 

 the destined boundary of its future abode : this being done, 

 it proceeds to excavate the cavity by throwing out the sand 

 by a process not less singular than effective. Placing itself 

 in the inside of the circle which it had traced, it thrusts the 

 hinder part of its body into the sand, and, with one of its 

 fore legs, serving as a shovel, it charges its flat and square 

 head with a load, which it immediately throws over the out- 

 side of the circle, with a jerk sufficiently strong to carry it 

 many inches. Walking backwards, and constantly repeat- 

 ing the process, it soon arrives at the part of the circle from 

 which it set out : it then traces a new circle within the first, 

 and excavates a second furrow ; then a third within this, 

 and so on, until, by a repetition of these operations, it ar- 

 rives at the centre. It never loads its head with the sand 

 lying on the outside of the circle, although it would be as 

 easy to do this with the outer leg, as to remove the sand 

 within the circle with the inner leg ; but it knows that it is 

 the sand within the circle that is to be excavated, and it 

 therefore constantly uses the leg next the centre. 



After the first series of circles is completed, a second, of 

 less diameter, and deeper, is commenced within it ; and so 

 on with others, until the hole assumes the shape of the im- 

 pression of an inverted cone, when the work is finished. 

 As the constant use of one leg during the whole of this ope- 

 ration, would necessarily exhaust the animal so much that 

 it would be compelled to waste much time in recovering its 

 strength, it adopts a plan which prevents this : the first cir- 

 cle is excavated with one foot ; it then turns completely 

 round, so that the second is excavated with the opposite 



