DR. HOOD — N^OTES OX THE MAT FLY. 109 



but iustoad of laying its eggs in the water, it lays them on the 

 leaves of trees which overhang the water. It is in season from 

 the last week in May until the end of June. The river Wandle is 

 mentioned by Izaak Walton in his book on angling, and he speaks 

 of the trout therein as being the finest to be found anywhere. It 

 is possible that they were so in his day, when the May fly might 

 have been a denizen of those waters — from which subsequently 

 pollution may have banished it, — but at present I think they are 

 not entitled to this venerable and worthy fisherman's distinction. 



When the May fly first comes to the surface of the water, it has 

 to shake off the case that confines its wings, to dry them, and to 

 gain a little strength in the new atmosphere it breathes, before it 

 can fly to enjoy its short existence. It generally manages to 

 shelter itself on a tuft of grass, when if the sun is shining it soon 

 takes to flight and hovers over the water. It now becomes the 

 prey of numerous birds as well as fish. I have watched the 

 difl'erent kinds of birds that prey upon it, and it seems to them all 

 a most tempting morsel. Swifts, swallows, martins, chafiinches, 

 water-wagtails, starlings, and even rooks do not disdain to catch 

 them when they are able. Perhaps the most amusing sight is to 

 watch the common sparrow attack the May fly. His flight is a 

 clumsy one, and he has no chance of securing his prey when on the 

 wing ; he therefore adopts a coarser but an effectual mode of 

 capture. He flies sharply at the May fly, and butts it so as to 

 knock it down, and then secures it. He takes care never to do this 

 unless the fly is over a bank of weeds, or off the water, for he 

 seems to know that if he acted otherwise, the fly would fall on 

 the water and it would be beyond his power to secure it. I have 

 seen the still parts of a river covered with the skins, or exuviae, of 

 the May fly, and frequently have noticed trout rise at them when 

 they have been floating down the stream, turning away from them, 

 however, in apparent disgust when they have discovered their mis- 

 take in grasping at a shadow instead of a substance. 



It would well repay any lover of the science of Entomology, 

 who possessed an aquarium, to trace the history of the May fly 

 from the egg. This might be done by obtaining some of the flies 

 from the surface of the water whilst engaged in depositing their 

 eggs, and removing them to the aquarium. The bottom of the 

 a(juarium should be composed of fine and coarse gravel, care being 

 observed to exclude therefrom all insects, fish, snails, etc., that 

 would be likely to prey upon the eggs, or larvae, when hatched. 

 In fact, the aquarium should be devoted exclusively to the occupancy 

 of the May fly's eggs. An examination of the cases in which 

 the caddis of the May fly is found would instruct the experimenter 

 as to the various materials he should place at the bottom of the 

 aquarium so as to be in readiness for the larva when it has arrived 

 at a certain age of growth to construct for itself a habitation. As 

 it is in streams and running water that the May fly deposits her 

 ova, the tanlc in whicli the eggs are deposited should be constantly 

 supplied with running water. If this experiment were carried 



