74 



to be typical of any one association. (Cf. Gates, 'iia: 22.) Their 

 influence, however, is felt by all the associations which contribute to 

 their food, and to that extent these animals which fly above the 

 bunch-grass, catching flying insects on the wing, are members of the 

 association. There is a second group of aericolous animals which 

 are normally at rest, perhaps on a perch or other prominent station 

 (sometimes on the bare sand), and which make occasional short 

 flights after their prey. The following list includes members of 

 both groups : 



Isclimira vcrticalis Chordciles virginianus virgini- 



Bpicordiilia princeps anus 



Sympetrum rnhicundnlnm Chaetura pelagica 



*Brytheinis siinpHcicolHs Tyrannus tyr annus 



Peritheniis doniitia Hirundinidae? 



*Proctacanthns spp. Chiroptera? 



Other Asilidae 



Robber-flies and the kingbird wait for their prey while at rest. 

 Not all the food of the robber-flies is taken in the air, and so they 

 are not exclusively aericolous. The other animals fly about during 

 most of their active period of the day. I have no record of the oc- 

 currence of swallows or bats, but they are to be expected in the 

 bunch-grass association. 



Herhicolous Predaceoiis Animals. — Most herbicolous predaceous 

 animals have little or no direct relation to the plant. They are found 

 on the plant becatuse the animals on which they feed are there. In 

 some associations rocks and stumps form as productive a hunting- 

 ground, to certain animals, as do plants, and webs of Drassidae and 

 TJieridiidoe are found there as well a'S on plants. In the sand prairie 

 one is as likely to find jumping-spiders on fence-posts (or any other 

 introduced objects) as on plants. The spiders feed on stray insects 

 which are almost always present. In effect there is little difference 

 between an elevated inanimate object and a plant, so far as most 

 predaceous animals are concerned. The fact that both are in the 

 same horizontal stratum makes them essentially similar as a habitat 

 for predaceous animals. 



Liobununi sp. Phyniata fasciata 



Thoniisidae Hymenarcys nervosa 



Steatoda corollata Perillus circiimcinctus 



Buryopis funehris Hippodainia parenthesis 



Bpeira stellata Chilocorus hividuerus 



