236 WASP STUDIES AFIELD 



caterpillars, flies, tent-caterpillars, spiders taken from mud 

 nests, or pupae of Trypoxylon. 



Ammophila, like all the others, is haunted by persistent 

 parasites. One little Dipteron often follows her like a bad 

 conscience, persisting unwaveringly for two hours or more 

 at a time as she drags her caterpillar here and yonder in 

 search of her hole, poising in mid-air, always about twelve 

 or fourteen inches behind her, advancing, retreating, turn- 

 ing with every movement of her leader, as if firmly attached 

 to her in some invisible way. If pictipennis lays her cater- 

 pillar down and leaves it for a time while she searches, 

 this parasite will sit down at her usual safe distance and 

 watch it until the owner comes back and claims it. Like 

 parasites of other wasps, it seems to have no interest in a 

 host left lying thus exposed, but is eager about it as soon 

 as it is taken away with a prospect of being buried properly. 



We are unprepared to make any statements regarding 

 the frequency of parasitization, but it is not uncommon, for 

 we have several times dug up nests only to find the cater- 

 pillar heavily infested with Dipterous or Hymenopterous 

 larvae instead of serving as nourishment for Ammophilas 

 larva. 



The adults, too, have their enemies. We once rescued a 

 pictipennis which was being carried off in the mouth of a 

 robber-fly, Proctacanthus milberti Macq., and Mr. George 

 M. Greene records 15 that he found the adults stylopized by 

 Eupathocera sp. 



The adults have been seen feeding on the nectar of the 

 dandelion, and Robertson 16 records them frequenting about 

 eight species of flowers. 



We have only once caught a glimpse of the mating of 

 this species. In the dooryard of a farm-house one June 



15 Ent. News 28 : 94. 1917. 



16 Trans. Acad. Sci. St. Louis 6: 455. 1894. 



