10 



it deserts in preference for our more abundant willows 

 and elms. The nettle and thistle have brought with 

 them from Europe some of their pecuhar insects,* which 

 happily are more serviceable than the weeds they have 

 accompanied. It cannot be denied that many of our 

 destructive insects are now spread far and wide through 

 those sections of the Eastern continent which have had 

 commercial intercom'se with America ; but it is evident 

 that we have not been gainers by an exchange ; for in 

 this country are now naturalized immense numbers of 

 foreign insects, whose ravages are by no means com- 

 pensated by the benefits derived from the Asiatic silk- 

 worm, at this time an object of so much interest to 

 statesmen and manufacturers, nor by those annually 

 abstracted from the European honey-bee, " the white 

 man's fly," now, through the instrumentality of our 

 forefathers, swarming even in the Western wilds of this 

 continent. 



It is of the greatest consequence, in devising reme- 

 dies for the injuries of insects, first to learn something 

 of their economy. Were our insect enemies at all 

 times as apparent as their ravages, preventive means 

 might more readily be adopted ; but many of them 

 are not only masked in various disguises during the 

 period of their devastations, but carry on their oifen- 

 sive operations only in the obscurity of the night, or 

 insidiously conceal themselves while performing the 

 work of destruction. Others, though their attacks are 

 made in broad day-light, and though they may, while 

 thus employed, be constantly exposed to our examina- 



* The Papilio Atalanla inhabits the nettle, the Papilio Cardui the 

 thistle. 



