xii TROUT FISHING 



It should, of course, he understood that 

 the lists in The Booh of Flies are not 

 to he considered absolutely rigid. As 

 regards weather one month glides into 

 another imperceptibly, and it is not to be 

 supposed that when any month is over all 

 the flies shown under its heading are ob- 

 solete for the season. For example, in The 

 Book of Flies the Mayfly appears under 

 the heading "June," because as a rvle 

 nature sends it forth in that month, 

 early; but now and then, in the South of 

 England, if the weather is propitious it 

 appears on the, streams towards the close 

 of the month after which it is named. 

 Similarly, most of the other insects, like 

 the cereals of the fields, are often a week 

 or two weeks early, or late, according to 

 the weather. The lists in The Book of 

 Flies, then, are to be considered as stating 

 the ascertained averages, not as a code 

 of inflexible time-tables. 



Although, if I be not mistaken. The 

 Book of Flies now presented is the first of 

 its kind, pictures of flies, arranged for 



