NO. 7 



PROTECTIVE ADAPTATIONS McATEE 



85 



birds which eat galls or fungi or which ohtain their food chiefly in or 

 about water, or which feed directly upon or l)y tearing up carrion and 

 the like. 



Bird enemies. — Until comparatively recently it was very difficult to 

 get identifications of flies found in bird stomachs, and even more so 

 of their larvae, hence nearly half of the identifications of Diptera 

 were not carried further than to the order. 



The large proportion of the unidentified to the total number of 

 records of Diptera has one advantage, namely that it is distributed 

 probably among nearly as great a number of species of birds as are 

 the records for all flies. Since that number exceeds 250, we may be 

 sure that there is no group of birds that hal)itually avoids Diptera. 

 Among these records are numerous instances of from 50 to 500 

 specimens of flies or their larvae being taken at a single meal, good 

 evidence that the flies concerned were not at all distasteful. These 

 data are sufficient commentary also on the state of determinations of 

 Diptera, scores of specimens being present and not being named even 

 to the family. The material will be re-examined in the future to 

 obtain more satisfactory results, but there has been no time for that 

 in connection with the present paper, which is wholly a by-product. 



A satisfactory discussion of the relations of birds to Diptera is 

 hardly possible therefore, and the best that can be done is to present 

 the fragmentary data available and to make allowances for deficiencies. 



Identifications of Diptera 



Percentage of 

 identifications 

 among those 

 Number of of all 



Family identifications Diptera 



Tipulidae 1,565 14-4426 



Dixidae 3 .0277 



Psycliodidae 5 .0461 



Qiironomidae 1,003 9.2562 



CuHcidae 112 1.0336 



Mycetophilidae 53 .4891 



Cecidomyidae 15 .1384 



Bibionidae 140 1.2920 



Simuliidae 8 .0738 



Blepharoceridae I .0092 



Rhyphidae i .0092 



Orphnephilidae 



Stratiomyidae 732 6.7553 



Tabanidae 336 3.1008 



Acanthomeridae 



* Computed from Aldrich, J. M., A catalogue of North 

 etc., Smithsonian Misc. Coll., vol. 46, pp. 1-680, 1905. 



Percentage 



of species 

 in this family 



among the 

 whole number 



of nearctic 

 Diptera ■* 



5.7309 

 .0922 

 •3920 



3.0903 



1-9257 

 2.9058 



1-6835 



•3173 

 .1384 

 .0807 



•01 15 



3-4362 



3.5285 



•I 153 



American Diptera, 



