THE SAND-LOVING AMMOPHILA 209 



The duration of her absence varies. Sometimes she meets 

 with early success in her foraging and returns with her 

 caterpillar in an hour; sometimes she is out as long as six 

 or eight hours, presumably in her search for prey. We have 

 never been so fortunate as to witness this part of her work. 

 We have seen her out foraging in the field, to be sure, 

 hopping from leaf to leaf or flying over the grass, scanning 

 the weeds as she lightly passes over them, but we have never 

 seen 'her at the critical moment of the capture of her prey. 

 But, sooner or later, she comes trudging home with her 

 burden, which often is a grey cut-worm. At this part of 

 her task she is, naturally, more conspicuous and more easily 

 discovered than at any other time. We must not be sur- 

 prised that she sometimes has some difficulty in progressing 

 with her load; rather we must be astonished that she can 

 move with it at all. The caterpillar is very often four times 

 her own weight, or more, yet she brings it through grass 

 and roots, clods and gutters. We have never seen an Am- 

 mophila give up a caterpillar because it was too heavy for 

 her. Sometimes, however, the prey is so small that she can 

 drag it with ease or even lift it clear of the ground and 

 make rapid progress. She practically always carries it in 

 the same manner; she turns it on its back so the smooth, 

 rounded back will slide on the ground like a sled-runner; 

 then she stands astride it, grasps the skin at the sides of 

 its throat until it is drawn to look like a tight collar 

 around the caterpillar's neck, lifts the anterior end a little 

 so only the rounded dorsum will touch the ground or ob- 

 stacles, and away she goes on all six feet. Once or twice we 

 have seen her grasp it by the middle segment instead of by 

 the throat, and lift it clear of the ground (fig. 46). On one 

 occasion, when a wasp was in grave difficulties in getting 

 her caterpillar through a tangle of grass, she managed it 

 very ingeniously by lifting one end of the burden and prop- 



