290 Miscellaneous. 



turned and began to circumambulate the pit. The agitation upon 

 the sand, slight as it was, generally (not always) aroused the grub 

 to actiou ; and by the process already described the sand was with- 

 drawn from beneath the feet of the insect, who slid along with the 

 tiny sand-avalanche into the apex. There it was seized, unless, as 

 sometimes occurred, it was fortunate enough to make its escape. 



The use of the long hooked mandibles of the grub appeared in the 

 act of seizure : the ants were held off " at arm's length," so to speak ; 

 and the grub thrashed or jerked them violently until they were 

 exhausted. Meanwhile the efforts at defence were made futile by 

 the distance from any vital point at which the victim was held. 

 Tetramoriuni ccespitttm, the pavement-ant, which has a sharp sting, 

 and tried eagerly to use it, was thus prevented from doing so and 

 made quite defenceless. So also the formidable pincer mandibles of 

 the carpenter ant, by which she excavates her wooden galleries and 

 decapitates her victims with the facility of a guillotine, are rendered 

 entirely useless. This defcncelessness is complet< d by the position 

 of the grub beneath the sand. A carpenter worker minor seized by 

 a hind leg bowed her body under to snap at her captor ; but her 

 jaws grasped only the gritty pellets of sand which covered the ant- 

 lion's head, and out of which the long hooks alone projected. 



The point of greatest importance in Dr. McCook's observations was 

 the continuation of the statements of M. Bonnet concerning the be- 

 haviour of the grub when its movements are obstructed by pebbles 

 too large to be tossed out by the head. This statement having been 

 seriously questioned*, the matter was tested by first dropping three 

 pebbles, each larger and heavier than the larva, within the centre 

 of the pit. The grub having attempted to move these in the usual 

 manner, and failed, proceeded in this wise: — It backed up to a 

 pebble, and placed the posterior of the abdomen against and a little 

 beneath it, so that the sand readily dropped over the apex of the 

 abdomen, and lay between that and* the stone. A little adjustment 

 was required to balance the pebble by getting its middle part against 

 the end of the body ; and then the animal began to back out of the 

 pit, so pushing the pebble before, or, rather, behind it, up the side, 

 and to a point a short way beyond the margin, where it was aban- 

 doned. A small furrow (two to three inches long) was described in 

 the sand by the moving stone, which furrow was curved from the 

 point of departure. The stone was kept perfectly balanced durin 

 the entire progress, which was quite rapid. Each of the three peb- 

 bles was thus removed, the grub returning each time and backing 

 it out of the pit. The experiment was repeated a number of times, 

 and always with the same result. Some wcll-roundt d stones were 

 selected, in order to make the difficulty of balancing greater ; but 

 this made no difference in the action of the larva, a round pebble 

 being balanced and removed quite ae readily as a flat one. It was 



* Rennie, < Insect Architecture,' p. 202 r— « We may be pardoned iox 

 pausing before giving full credence to these details." 











