TABANID^ OF OHIO. I3. 



' ', Many species of Tabanus have the wings entirely transpar- 

 ent while others have dark areas which furnish distinctive char- 

 acters. In T. sulcifrons dark markings are located at the bifur- 

 "cation of the third vein and along the veins at ;the discal end of 

 the discal cell ; when markings are present on the wings of the 

 various species- of Tabanus it is more common to find them where 

 the third vein branches, and along the veins or parts of veins 

 'which are most nearly transverse. Exceptions to this may be 

 seen by reference to venustus and turbidus. 



Abdomen. The markings of the abdomen in this species 

 consist of rather' broad white triangles and white posterior mar- 

 gins on most of the segments. These markings are formed by 

 the color and arrangement of the vestiture, which consists of 

 hairs and dust or pollen. With a bristle brush the hair may be 

 easily removed from a dry specimen, but on the same kind of 

 a specimen the pollen is more persistent and therefore more read- 

 ily removed by rubbing after it has been moistened. 



When all the vestiture has been removed the abdomen is 

 nearly a uniform brown all over and appears quite different than 

 in a perfect specimen. 



Seven segments are visible to the unaided eye. The circum- 

 ference decreases from the second backward, and concealed by 

 the seventh or smallest are what may be considered as three very 

 much reduced additional segments, which are easily removed by 

 the aid of a needle and which can only be differentiated satisfac- 

 torily by the use of a microscope or strong lense. These segments 

 besides being smaller are much modified in both sexes. In the 

 female from ventral view, is visible a sclerite, infraanal platej 

 which is interesting from a specific standpoint, and its form may 

 be seen best by reference to Fig. 9, q. plate I. 



The claspers of the male are borne by the eighth segment, 

 each of these are composed of two joints, which are movable ; 

 therefore they appear different in different specimens as may be 

 .-lecn by reference to the figures, plate I, Figs. 6 and 10. 



MALES COMPARED WITH FEMALES. 



The males and females in the entire family are easily dis- 

 distinguished from the fact that the former sex has the eyes con- 

 tiguous and the latter has the eyes plainly separated. In all the 

 species studied the male has the proboscis longer and slenderer, 

 and the front feet larger than in the female. The palpi in the 

 female point downward and the second segment is carried in 

 front of the proboscis, while in the male they often turn upward 

 and the second segment is carried against the face. 



Usually the males and females of the same species are easily 

 associated, but in a number of species it is not an easy matter at 

 least until they have been taken in the same locality in the field. 



