226 WASP STUDIES AFIELD 



a certain spot in the broad, barren area, where it began to 

 dig. It would stand squarely on its head and hum a 

 high-pitched little tune while at work. In digging, the man- 

 dibles and forelegs were used to chop and break the dry earth 

 while the middle legs were used to brush the dust away at 

 both sides. At first there was nothing to be brushed away, 

 yet this pair of legs worked automatically and prettily. 

 There was no sign of the usual habit of carrying the exca- 

 vated dirt away to a pile, as is always done when the burrow 

 is being dug. With the hind legs alone the wasp held firmly 

 to the ground. It left the spot several times, as if in doubt 

 or dissatisfied about something, but returned. In a few 

 minutes a neat depression was made; then without provo- 

 cation or without warning or flight of orientation, it arose 

 and flew far away, never to return. Was it in quest of 

 prey, which in this instance it did not find, or are we mis- 

 judging it in this suspicion? 



We have never found A. pictipennis to provision her nest 

 with more than one caterpillar, although the Peckhams 

 found that A. urnaria stores two caterpillars in each nest. 

 Williston 7 finds that A. yarrowi Cr. stores four or five cat- 

 erpillars, and Hartman 8 says that the large A. procera "cap- 

 ture and store but one immense green tomato caterpillar, 

 while the smaller specimens of procera bring in three cater- 

 pillars. Kellogg 9 finds that an Ammophila sp. which in- 

 habits the salt marshes near Stanford University uses from 

 five to ten paralyzed inch-worms for each young wasp. 

 According to Sharp, 10 A. hirsuta chooses a single larva, 

 of considerable size, belonging to one of the nocturnal 

 Lepidoptera. Fabre 11 finds that A. jnlii stocks each 



7 Bull. Wis. Geol. & Nat. Hist. Surv. 2: 25. 1898. 



8 Bull. Univ. Tex. 66 : 13. 1905. 



9 Am. Insects, p. 494. 



10 Insects, Pt. 2, p. in. 1895. 



11 Hunting Wasps, pp. 259, 419. 1917. 



