108 



4- Loiv Prairie Association 



The moist black soil prairie, a degree removed from the wet or 

 swamp condition, with ground water in the sprmg relatively near the 

 surface is fairly well characterized by the rosin-weed (Silphmm), par- 

 ticularly S. terebinthinaceum. Other plants likely to be associated with 

 S terebinthinaceiim are Silphium laciniatum and S. integnfohum, 

 Bryngium yiiccifolium, Lepachys pinnata, and, to a less degree, Lac- 



tiica canadensis. j i Ci. 4.- t 



In the Charleston area this condition is represented by btation i, a, 

 north of the town, and Station III, a, and in part b, east of the town. 

 The proximity of ground water is shown at Station I, ^, by the pres- 

 ence of crawfish burrows, probably those of Cambants gracilis. At 

 Station III the proximity of water was also evident where 5-. terebin- 

 thinaceum was most abundant in the railway ditches. Such perennial 

 plants are indicative of the physical conditions for a period of years, 

 and are thus a fairly reliable index of average conditions— much more 



so than the annuals. , . • ^- r 



It is difficult to decide which kinds of animals are characteristic ot 

 this kind of prairie. Provisionally I am inclined to consider the fol- 

 lowing as being so: Cambariis gracilis; Argiope aurantia; the grass- 

 hoppei-s Bncoptolophus sordidus, Melanoplus differentialis, M. femiir- 

 riibrmn Scudderia texensis, and Xiphidinm strictnm; CEcanthus nign- 

 cornis; Phymata fasciata; and asilids. The presence of Lepachys was 

 clearlv an important factor in determining the presence oi Melissodes 

 obliqua and Bpeolus concolor. At Station III, b, east of Charleston 

 Bpicauta pennsyhmiica and Bombus penmylvamcus, auricomus, and 

 ifnpatiens were taken on the flowers of Silphium terebinthinaceum. 



Robertson ('94, PP- 463-464; '96b, PP 176-177) h^^s published lists 

 of insect visitors to the flowers of Silphium and Lepachys ( 94- PP- 

 468-469), at Carlinville, 111. Recently Shelford ('13a, p. 298) has 

 published a long list of animals inhabiting Silpldum prairie near Chi- 

 cago. Forbes CQO, P- 75) has reported the snout-beetle Rhynchites 

 hirtus Fabr. as feeding upon Silphium integnfolimn. 



In a colony of prairie vegetation at Seymour, 111., which mcUided 

 much Silphium and Bryngium, the following insects were taken Octo- 

 ber 7 from the ball-like flower clusters of Bryngium yucci folium: the 

 bugs Lygcrus kalmii, Thyanta custator Fabr., Buschistus z'anolanus 

 ^nd Trichopeplasemivitt'ata Say (No. 539, C. C. A.^ the last named 

 in large numbers, the nymphs in several sizes as well as the_ adults, a 

 fact which suggests that both may hibernate upon the prairie. _ Kob- 

 ertson ('89, PP- 455-456) has summarized his collections oi insects 

 from Bryngium and on Buphorbia corollata ( 90a, pp. 74-/5;- 



