232 DIPTEEA OR TKUE FLIES. 



last segment (in Tahanus hovinns). The Tabanid» are chiefly- 

 abundant in well-wooded places, especially where water is near. 

 The warmer the day the more ravenous and bloodthirsty the 

 females become — at least that is my experience in Norway and 

 Switzerland, where animals suffer much more from them than 

 they do even in the New Forest. Tabanidse can produce a loud 

 buzzing noise, and frighten stock, just as do the Warble-flies, 

 but the noise made by Tabanidse is much sharper than the 

 dull hum of the CEstridae. In tropical countries they are great 

 pests. 



A plan to keep these pests off horses that I have seen 

 employed in the Bernese Oberland is to dress the horses over 

 with paraffin-oil and soap, rubbed with a sponge, and also with 

 walnut juice. Miss Ormerod mentions soluble phrenyl as 

 useful in one of her reports, but at present no substance is 

 known that has any great effect in this direction. 



Other flies belonging to the section Cydorrhaplia are divided 

 into the Prohoscidca and Epruho^riiJea. The Proboscidea con- 

 tain the majority of flies, the following being some important 

 economic groups : — 



Hover-flies, or Syrphidae. 



The Syrphidfe are all moderate-sized flies, often brilliantly 

 coloured, generally with banded bodies, yellow or white and 

 black or brown being the predominating colours. They hover 

 in the air like a hawk, suddenly darting ofl" and again remain- 

 ing hovering at a fresh spot. "We only see them in the bright 

 sunlight, and may notice them flying and hovering over plants, 

 upon the nectar of which the adults feed. At other times we 

 see them busy over colonies of Aphides, for here they deposit 

 their eggs, their curious, almost repulsive-looking larvae (fig. 

 128, 2 and 5) feeding upon plant-lice, which they devour with 

 great rajjidity. The larvm are yellow, green, or red in colour. 



