222 THE WOODLANDS. 



CHAPTER XII. 



TWO- WING ED FLIES. 



TWO-WINGED Flies, or Diptera, as they are called by 

 entomologists, are exceedingly numerous. There are 

 said to be not less than ten thousand species in 

 Europe distributed through six hundred and eighty 

 genera, but in this country their study is exceedingly 

 limited, yet the number must be very large. Their 

 habits are very variable. The greater number act as 

 scavengers in the water and on the land, and thus 

 become sanitary agents. They are the earliest to 

 appear in spring, and the latest to depart in autumn. 

 Active at all times, by night and by day, in rain or 

 in sunshine, most of them prefer the latter. This 

 book has no pretension to being a guide to species, 

 or the task here would be a formidable one, and there- 

 fore we shall rest content with brief allusions to some 

 of the most important groups. Of these the Gnat 

 family need not detain us ; for although some of them 

 fly in woods, they are more associated with the ponds 

 and ditches in which the larvae are reared. The two- 

 winged gall-flies are termed Ceddomyidce, and these 

 on the contrary are addicted to vegetation of all 



