1910] Graenicher, Bee-Flies in Their Relations to Flowers. 99 



claimed, as mentioned above, that they exhibit a decided prefer- 

 ence for flowers with exposed nectar. 



A glance at the list of flowers visited by Anthrax altemata 

 shows that 7 of these belong to the type with exposed nectar, while 

 in the remaining 5 ( 4 Composite and Verbeha hastata ) the nectar 

 is concealed. Of the 6 flowers visited by the same insect at Carlin- 

 ville, 111., only 1 has exposed nectar ( Euphorbia corollata). 



For Anthrax halcyon we And all of the flowers visited at Mil- 

 waukee as well as at Carlinville belonging to the Composite, 1. c. 

 with concealed nectar. In those figuring in the Milwaukee list the 

 nectar is concealed at the bottom of tubes ranging in length from 



1 mm., 5 as in Bupatorium perfoliatum and the 2 species of Soli- 

 dago, to 4 or 4.5 mm. (Bupatorium purpureum and Helianthus 

 strumosus) . 



In the case of the 4 additional species of Anthrax referred to 

 above (fulviana. lateralis, parvicomis and sinuosa) only 1 of the 

 species of flowers visited ( Tohcldia glutinosa ) has exposed nectar. 



As to Spogostylum (of which Argyramwba mentioned by 

 Knuth is a synonym ) Monarda fistulosa visited by 5. albofascia- 

 tum, and Bupatorium it rtiar folium visited by S. wdipus are both 

 flowers with concealed nectar. 



Summing up our results for the 6 species of Anthrax, and the 



2 species of Spogostylum observed at Milwaukee we note that 

 among the 31 species of flowers visited 8 or only 26% have ex- 

 posed" nectar. The statement that the short-tongued bee-flies 

 belonging to the genera Anthrax and Spogostylum (Lomatia, the 

 third genus referred to in this connection in Knuth's Handbook 

 does not occur in our region ) prefer flowers with exposed nectar 

 does not hold good for our region. 



III. RELATIONS OF BQMBYIylDS TO SOCIAL FLOWERS. 



The Composited are the most important among the so-called 

 social flowers. In the temperate regions of our North American 

 continent they occupy a prominent position in the make-up of 

 the flora. In the latest list of the flora of Milwaukee County 

 published by Mr. Howland Russel' 1 921 'species of ferns and flow- 

 ering plants are enumerated, and the Composita 1 figure in this list 

 with 152 species or 16.5% of the flora. Data obtained from speci- 

 mens in the herbarium of the Public Museum of Milwaukee, as 



5) S Graenicher: Wisconsin flowers and their pollination. Compositae. 

 Bull. Wis. Nat. Hist. Vol. VII. pp. 19-77. (1909). 



6) Howland Russel, Check list of the flora of Milwaukee County. Bull. 

 ns. Nat. Hist. Soc. Vol. V, pp. 167-250 (1907). 



Wis. 



