INSECTS AND VERMES 429 



exceed the males in bulk, dart and shoot along on the 

 surface of the water with the males on their backs. When 

 a female chooses to be disengaged, she rears, and jumps, 

 and plunges, Uke an unruly colt ; the lover thus dis- 

 mounted, soon finds a new mate. The females, as fast 

 as their curiosities are satisfied, retire to another part of 

 the lake, perhaps to deposit their foetus in quiet ; hence 

 the sexes are found separate, except where generation is 

 going on. From the multitude of minute young of all 

 gradations of sizes, these insects seem without doubt to 

 be viviparous. 



PHALAENA QUERCUS 



Most of our oaks are naked of leaves, and even the 

 Holt in general, having been ravaged by the caterpillars of 

 a small phalaena which is of a pale yellow colour. These 

 insects, though a feeble race, yet, from their infinite 

 numbers, are of wonderfiil effect, being able to destroy the 

 foliage of whole forests and districts. At this season they 

 leave their aureliae, and issue forth in their fly-state, 

 swarming and covering the trees and hedges. 



In a field at Greatham, I saw a flight of swifts busied in 

 catching their prey near the ground ; and found they were 

 hawking after these phalaenae. The aurelia of this moth 

 is shining and as black as jet; and lies wrapped up in 

 a leaf of the tree, which is rolled round it, and secured 

 at the ends by a web, to prevent the maggot from falling 

 out. 



EPHEMERA CAUDA BISETA. MAY FLY 



June 10, 1 77 1. Myriads of May flies appear for the 

 first time on the Alresford stream. The air was crowded 

 with them, and the surface of the water covered. Large 

 trouts sucked them in as they lay struggling on the 

 surface of the stream, unable to rise till their wings were 

 dried. 



