MAV-FLIES 44 1 



gradually, part at a time, and deposit tliein in one or other of 

 the following manners: either the mother alights upon the 

 water at intervals to wash off the eggs that have issued from 

 the mouths of the oviducts during her flight, or else she creeps 

 down into the water to lay her eggs upon the under-side of 

 stones, disposing -them in rounded patches, in a single layer 

 evenly spread, and in mutual contiguity." The eggs are very 

 numerous, and it is thought may sometimes remain in the 

 water as much as six or seven months before they hatch. 



The number of individuals produced by some kinds of may- 

 flies is remarkable. Swarms consisting of millions of individuals 

 are occasionally witnessed. D'Albertis observed Palingenia 

 papuana in countless myriads on the Fly Eiver in New Guinea : 

 " For miles the surface of the river, from side to side, was white 

 with them as they hung over it on gauzy wings ; at certain 

 moments, obeying some mysterious signal, they would rise in 

 the air, and then sink down anew like a fall of snow." He 

 further states that the two sexes were in very disproportionate 

 numbers, and estimates that there was but a single female to 

 every five or six thousand males. 



Ephemeridae in the perfect state are a favourite food of 

 fishes, and it is said that on some waters it is useless for the 

 fly-fisher to try any other lure when these flies are swarming. 

 Most of the " duns " and " spinners " of the angler are 

 Ephemeridae ; so are several of the " drakes," our large U. danica 

 and E. vulgata being known as the green drake and the gray drake. 

 Eonalds says ^ that the term " dun " refers to the pseud-imago 

 condition, " spinner " to the perfect Insect, E. danica and E. 

 vulgata are perhaps not distinguished by fishers ; Eaton says 

 that the former is abundant in rapid, cool streams, while E. 

 vulgata prefers warmer and more tranquil rivers. 



These sensitive creatures are unable to resist the attractions 

 of artificial lights. Eeaumiir noticed this fact many years ago, 

 and since the introduction of the electric light, notes may 

 frequently be seen in journals recording that myriads of these 

 Insects have been lured by it to destruction. Their dances may 

 frequently be observed to take place in peculiar states of light 

 and shade, in twilight, or where the sinking sun has its light 

 rendered broken by bushes or trees ; possibly the broken lights 



1 Fly-Fisher's Entomology, 4tli ed. 18-19, p. 49. 



