28 Bulletin Wisconsin Natural History Society. [Vol. 7, Nos. 1-2. 



and food habits. In comparing the lists of visitors of the different 

 flowers by statistical methods I have found Loew's classification 

 very helpful. He divides the flower visiting insects into the fol- 

 lowing groups : 



EUTROPOUS INSECTS. Completely adapted flower visitors of the 

 greatest value for pollination. 

 Hymenoptera : Long-tongued bees. 

 Lepidoptera: Hawk moths (Sphingidae). 



HEMITKOPOUS INSECTS. Partially adapted flower visitors of mod- 

 erate value for pollination. 



Hymenoptera: Short-tongued bees and certain wasps (family 

 Eumenidse, Bcmbcx, Ammophila and related genera among 

 the fossorial wasps, and Parnopes among the Chrysididae). 



Diptera: Three families of specialized flies (Conopids, Syr- 



phidae and Bombyliida?) . 

 Lepidoptera: Butterflies and moths (except the hawk moths 



which belong to the first group). 

 Coleoptera : Specialized beetles (Nemognatha). 



ALLOTROPOUS INSECTS. Unequally and only slightly adapted 

 flower visitors of little value for pollination. 

 This group includes the remaining beneficial flower visiting 

 insects. 



A fourth group of dystropous insects (not adapted to pollina- 

 tion) is made up of harmful visitors such as flower destroying 

 grasshoppers, beetles, etc., or useless visitors such as ants, etc. 

 This group is of hardly any importance in the matter discussed 

 in this paper and will not be considered at all. 



A grouping of the 562 insects of our list according to Loew 

 furnishes the following arrangement : 



EUTROPOUS. 



HYMENOPTERA. 69 Long-tongued bees, Nos. 1—69. 



LEPIDOPTERA. 1 hawk-moth, No. 484. 

 Altogether 70 eutropous visitors. 



HEMITROPOUS. 



HYMENOPTERA. 67 short-tongued bees, Nos. 70—136. 



26 wasps belonging to the families Eumenidse, Bembecidse and 

 Sphecida?, Nos. 142— 155 ; 186—188; 196—204. 



DIPTERA. 73 flies belonging to the families Bombyliidae. Syrphidae 

 and Conopidse, Nos. 270—284 ; 287—336 ; 337—344. 



LEPIDOPTERA. 59 butterflies and moths, Nos. 446—483; 485—505. 

 (All of the Lepidoptera except the hawk-moth No. 484, 

 which is eutropous.) 



COLEOPTERA. 1 long-tongued beetle, No. 536 (Nemognatha rittlgera). 

 Altogether 226 hemitropous visitors. 



