FOSSORIAL HYMENOPTERA 
445 
burrow, and having to reopen it, and pass down a tunnel, 
is wanting, she is unable to feed the larva. Indeed, she is 
unaware of its existence, although she may actually walk 
over it in her frantic searching for the mouth of the burrow 
which does not exist, while the precious larva she is impelled to 
feed slowly perishes in the sun. 
Again, I have seen the following in the case of a Sphegid 
which stores up a single large caterpillar. If the paralysed 
prey be removed from the burrow and laid on the ground, 
the Fossor, on her return, will pounce on it and sting it again, 
precisely as if it were a fresh one, although, from the intelligence 
supposed to be employed, she should recognise it, especially 
as she had laboriously carried it a long way ! 
Moreover, the stinging of the prey, always supposed to be 
a marvellous instance of intelligent skill directed towards 
a selective paralysis of the main nervous centres, has been 
shown by the Peckhams to be very far from perfection. They 
found by examining a large number of cases among different 
species, and even individuals of the same species, every degree 
of difference between a prey that was so seriously stung that it 
succumbed, and, drying up, would not afford the juicy food 
that the larva requires, and the other extreme where the prey 
was so lightly injured that it very soon recovered all its powers 
of movement. 
In the south of Europe, I remember finding the first Fossors 
at work that I had ever seen, and was much delighted. One 
was a species of Sphegid (. Ammophila ) which stored up a single 
large caterpillar. On one occasion, I had waited until the 
wasp had flown away after completing the series of operations, 
and then dug up the caterpillar with the egg affixed to its side. 
When put in a box the caterpillar was able to rid itself of the 
egg, and walked about and ate its food, though later it died. 
Similarly, every degree of perfection may be found in the 
operations of bestowing the prey in the burrow. It may be 
said here that the usual method is to prepare a burrow and 
then fly off and hunt for the prey, which has then to be brought 
back. Very often, as when it is a large Noctuid caterpillar , 1 
1 I have never noted a hairy or spiny caterpillar of a moth to be attacked 
by Fossors : the species seem always to be Noctuidce or Geometridce. 
