NATURAL HISTORY. 



845 



blights. Other insects it is true, 

 more especially the larvse of some 

 of the lepjdopfera, as those of the 

 pliahence tortrkcs, disfigure and do 

 infinite miscliief to plants, by roll- 

 ing and curling up the leaves ; 

 but these for the most part confine 

 themselves to certain trees and 

 plants. Their ravages are also 

 of shorter duration, being confined 

 to the growth of one brood, and 

 they are also less fatal. It Mould 

 be no difficult matter for me to 

 fill a volume with observations, 

 to which I have been an eye-wit- 

 ness, of the injuries which plants 

 sustain from insects ; but that 

 would be foreign to my present 

 purpose, which is to shew that the 

 aphis is the grand cause of these 

 diseases, and to place the iiwchis 

 operandi or manner in which they 

 effect this business, in its true light. ' 

 " W'e are fully aware that CLrtain 

 gregarious insects may, at parti- 

 cular times, rise up in the air, and if 

 small and light, be impelled by any 

 wind that may chance to blow at 

 the, time; and on this principle 

 we account for that shower of 

 aphides described by Mr. White 

 to have fallen at Selborne. But 

 certainly this is not the mode in 

 which those insects are usually 

 dispersed over a country, the 

 phoenomcnon is too unusual, the 

 distribution would be too partial ; 

 for the aphides, while at their 

 highest j)oiiit of multiplication, do 

 not svvarm like bees or ants, and 

 fly off in large bodies ; but each 

 male or female aphis, at such pe- 

 riods as they arrive at maturity, 

 marches or flies off without wait- 

 ing for any other. Yet it may 

 haj)p(ii, (hat from a tree or plant 

 thickly b("ii!t with them, iiunibi-rs 

 may lly o-fl. or emigrate together, 



" being arrived at maturity at the 

 " same moment of time. Detaching 

 " itself from the plant, each pursues 

 " adifferentroutc,intenton thegreat 

 " business of multiplying its species; 

 " and settles on such plants in the 

 " vicinity as are calculated to afford 

 " nourishment to its young. The 

 " common green aphis, which is so 

 " generally destructive, lives during 

 " the Minter season on such herba- 

 " ceous plants as it remained on 

 '• during the autumn, either in its 

 " egg or perfect state. If the wea- 

 " thcr be mild, it multiplies greatly 

 " on such herbage; as the spring 

 " advances, in May, the males and 

 " females of these insects acquire 

 "wings; and thus the business of 

 " increase, hitherto confined, is 

 " widely and rapidly extended, as 

 " the winged aphides, by hop-plant- 

 " ers called the fly, may be seen at 

 " this period very generally sitting 

 " on plants, and floating in the air, 

 " in all directions.'' 



Mr. Curtis, in the preceding ob- 

 servations on the genus aphis, having 

 mentioned the shower of aphides re- 

 corded by Mr. White, it cannot but 

 be agreeable to the reader to be 

 made acquainted with so curious a 

 phenomenon, in the words of its 

 describer. 



" As we have remarked above, 

 " that insects arc often conveyed 

 " from one country to another, in 

 " a very unaccountable manner, I 

 " shall hero mention an emigration 

 " o( small aphides, which was ob- 

 " served in the village of Selborne, 

 " no longer ago than Augu?: the 1st, 

 '' 1785. At abo.ut three o'clock in 

 " the afternoon of that day, which 

 " was very hot, the people of this 

 " village were surprised by a shower 

 " of aphides or sniother-flics, which 

 " fell in these parts. Those that 



" were 



