340 OBSER VA TIONS ON INSECTS. 



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. — White* 



PHAL^NA QUERCUS. 



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

 in general, having been ravaged by the caterpillars of a 

 small phalcena which is of a pale yellow colour. These 

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

 are of wonderful efiect, being able to destroy the foliage of 

 whole forests and districts. At this season they leave their 

 aurelia, 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 phalcence. The aurelice 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. — White. 



I suspect that the insect here meant is not the phalcena 

 quercus, but the phalcena viridata, concerning which I find 

 the following note in my Naturalist's Calendar for the year 

 1785 :— 



About this time, and for a few days last past, I observed 

 the leaves of almost all the oak-trees in Denn copse to be 

 eaten and destroyed, and, on examining more narrowly, saw 

 an infinite number of small, beautiful, pale green moths 

 flying about the trees ; the leaves of which that were not 

 quite destroyed were curled up, and withinside were tho 



