22 



Marvels of Insect Life. 



The Alder- Fly. 



This is one of the angler's Insects, and it is probably to him that it is 

 indebted for having an English name, for there is nothing about it sufftciently 

 attractive or striking enough to warrant it being distinctly labelled with a folk-name. 

 It has a general resemblance to the stone-flies and caddis-flies. It may be seen 

 pretty commonly sitting upon trees and fences near slow or stagnant water, with 

 its wings folded over the back, forming a ridge that completelv hides the bodv. 



When the wings are spread 

 there are seen to be four 

 of them, of a yellow-brown 

 colour and strongly netted, 

 the hinder pair being a 

 little smaller than the 

 others. Its flight is very 

 heavy, and not sustained. 

 In its grub state it is 

 a water Insect, but not 

 like some, absolutely de- 

 pendent upon being in 

 water ; a moist atmo- 

 sphere among vegetation 

 will sustain it for a time 

 at least. Often it has to 

 begin life as a terrestrial 

 creature, for its mother 

 frequently makes the 

 mistake of attaching her 

 mass of eggs to vegeta- 

 tion at some distance 

 from the water. After 

 all, though, this may not 

 be a mistake, but a 

 means of weeding out the 

 least fit ; for the egg-mass 

 contains from two to three 

 thousand eggs, and it is cc>rtain that more than 99 per cent, of these must perish 

 either as eggs, grubs, or chrysalids if this vear's generation of alder-Hies is not 

 largely to exceed that of last year. It is probable that the majority perish as 

 grubs from the attacks of other creatures in their search for th(> nearest water. They 

 are shrimp-like creatures, with a pair of curved, sharp-pointed jaws for attacking 

 the other aquatic animals upon which they prey. The hind-body bears sevcMi 

 pairs of jointed tilaments and a long, unjointed tail. These serve as gills for the 



Photo by] 



[If. /. Liuas, F.E.S. 



The Alder-Flv. 



The two S(;xcs arc here shown, the iiialc with expanded wings, the female with them eln>,d. 

 They may be found sitting on tree trunks and fences. The mass of several thou^anil 

 eggs are often attached to the leaves of trees, though the grubs live in water until tlirv ar.- 

 about to change to the chrysalis condition. The actual size is a littlr niorr than an imli 

 across the spread wings. 



