﻿292 S. A. NEAVE — NOTES ON THE BLOOD-SUCKING 



allies seem to be most usually found iu the neighbourhood of large bodies of 

 water, on the larger rivers, the shores of lakes, etc. 



The male Tabanus is not nearly such a sluggish insect as that of Haematopota 

 or Chrysops. They are usually very wary, especially when drinking at damp 

 sand in hot sun, and it requires a sharp eye and a long-handled net to capture 

 them. 



The eyes of the majority of species are very striking objects in life. Those of 

 the male consist of two portions, as described already in many other genera of 

 Tabanidae :— (1) a lower portion, composed of small facets, which also extends 

 as a very narrow line round the whole upper margin of the eye, this small- 

 facetted area being, in my experience, invariably of the same colour as the whole 

 eye in the female£of the same species ; (2) an upper portion, formed of large 

 facets, which is usually of a different colour or pattern. 



The African species of the genus Tahanus may be roughly classified by their 

 eyes. Thus, there are two groups with translucent spotted eyes. The first of 

 these comprises only T. maeulatissimus and T. irroratus. The second includes 

 T. ditaeniatus and its allies. These groups both exhibit the exceptional condi- 

 tions in which there is no difference in colour (at least, in the males of those 

 species which are known) between the upper and lower portions of the male eye, 

 though there is sometimes a difference in the size of the spots in the two areas. 

 It should be noted that the translucent eyes of these insects nearly always turn 

 to a more or less opaque dusky colour immediately after death. 



The species which have unicolorous green or bluish-green eyes in the female, 

 such as T. africanus, T. thoracinus, T. par, etc., have also the upper part of the 

 male eye unbanded and usually of a bronze or golden colour. Other species 

 which have a dusky unicolorous eye in the female, such as T. coniformis, 

 T. crocodilinus, T. sandersoni and T. leucostomus, have the upper part of the 

 male eye of various shades of shining grey or greyish bronze. 



A very important group, including T. taeniola and the many species allied to 

 it, have a unicolorous dark eye in the female, while the upper portion of the male 

 eye is grey or sometimes nearly white, with a distinct dusky band across both 

 eyes, which in some species is much broader at the junction of the eyes than at 

 the outer margins, and has the form of a somewhat elongate lozenge. The shape 

 or development of this band is of no diagnostic value, as it varies a good deal in 

 individuals of the same species, and is occasionally evanescent. 



Another group of rather small, black and white species, such as T. grains, 

 T. sharpei, T. velutinus, etc., have the eyes brilliantly banded with crimson and 

 green or blue in both sexes. In these cases, in the upper portion of the male 

 eye the bands are represented, but are much less brilliant and less clearly defined 

 than in the lower portion or in the whole of the female eye. 



A smaller group of rather similar black and white insects, including T. atri- 

 manus and T. variabilis, or species nearly allied to them, have dusky, unbanded 

 eyes in both sexes, the two portions of the male eye being of the same colour. 

 In the case of these species also the male eyes are relatively smaller than in the 

 foregoing group. 



The recently described T. pertinens, Aust., stands by itself, in my experience, 

 in having a combination of bands and spots in its eyes. 



