48 OHIO BIOLOGICAL SURVEY 



above (See pp. 37-40). I would simply add here the following note 

 from Wheeler, Psyche, July, 191 1: 



"The occurrence of such bulky and defenseless Dipteron larvae in the 

 nests of large-eyed active ants like the Pseudomyrmas, which are, more- 

 over, provided with powerful stings, is nearly as surprising as their occur- 

 rence in the nests of I'espa.'' 



(9) I have no data to give on this relation. It seems however, 

 scarcely possible that such succulent creatures as the larvae of Syrphidae 

 would not be picked up by birds for food. The aquatic larvae might be 

 attacked by predaceous animals but many of the media in which they thrive 

 are of such an offensive nature as to repel many animals. 



( 10 ) The report on which this division is founded is cited on page 40. 



ECOIvOGICAL RELATIONS AND ECONOMIC 



IMPORTANCE OF ADULTS 



Relations to Plants. Adult Syrphidae, so far as we know, are 

 almost all dependent upon the products, nectar and pollen, of the flowers 

 of Spcrmatophyta for their food. In their visits to flowers for the purpose 

 of feeding they inevitably carry about with them some of the pollen- 

 grains to be shaken, brushed or scraped off in other flowers. In this way 

 it is believed that various species of Syrphidae enter into an important 

 relationship to many kinds of entomophilus plants. The importance of 

 this relation will vary with the kinds of plants visited, the adaptation of 

 the body of the fly which can carry pollen, the feeding habits of the fl}', 

 and so forth. 



All of these points are deserving of much careful study but accurate 

 data seem largely to be wanting. To the ordinary observer it would seem 

 that Syrphidae visit all sorts of melliferous flowers indiscriminately; and 

 this is no doubt true of many of them, perhaps all. If there are any 

 cases of particular or specific interdependence of certain plants and certain 

 Syrphidae, I am not aware of it. Adults of Mesogramma polita feed on 

 pollen of corn (Ashmead). Mesogramma polita, Eristalis vineioruni and 

 Baeeha fuscipciuiis were observed by Ashmead feeding on the pollen of cot- 

 ton blossoms. A number of fruit trees, while in blossom, are regularly 

 visited by these flies in goodly numbers. I would also call attention to two 

 articles on"Insect Pollination at Cedar Point, "-'^ in which a dozen species 

 of Syrphidae are recorded as visiting certain flowers. According to Dr. 

 J. B. Smithf Erista/is fe)iax\s said to be entirely responsible for the pollen- 

 izing of chrysanthemums in green-houses. 



♦The Ohio NaturnUM, Vol. XI, No. 8, Vol. XII, No. G. 

 +Econ. Ent. 2nd. Ed. p. 348. 



