THE OLIVE DUNS 29 



species of the genus Baetis, and for all practical 

 angling purposes they are fully justified in so 

 doing. The differences between the species lie 

 mainly in the form of the sexual forceps of the 

 male, and can only be distinguished by the aid 

 of a powerful glass. As appears in the heading, 

 five species are merged in the name olive dun. 

 One of the distinguishing features of the genus 

 is the broad few-veined 

 hind-wing, of which a 

 figure is here given 

 (Fig. 4). 



The olive dun is the 

 sheet-anchor of the fisher- FIG. 4. Hind-wing of 

 man, and is present olive spinner, 



during every month of 



the fishing season. The dark olive appears 

 in the winter and spring, and its identity has 

 not yet been determined. Whether its distinc- 

 tive colour is a mere variation or is peculiar to 

 a particular species is as yet uncertain, and 

 further investigation will be required to throw 

 light upon this point. 



When spent, the female olive spinner assumes Red spinner 

 the reddish-brown, or dead-leaf colour, which 

 has given rise to the popular name " red 

 spinner." 



