52. What other physical conditions favor them ? 



53. What physical conditions are most unfavorable tc them ? 



54. What physical or other conditions cause them to migrate? 



55. How far has their migratory flight been known to extend ? 



56. What times do they prefer for migrating ? 



57. What vegetable or other substances are repugnant to 



them and what do they prefer? 



58. Do odors of any kind affect them in any particular way ? 



59. Through how extended a district have their ravages been 



noticed ? 



60. What remedies have been used to prevent their ravages ? 



61. How far has each remedy been successful ? 



A very small amount of time appropriated to observing these 

 insects may bring about results of the most weighty importance. 

 It is useless to attempt to prevent the destruction occasioned by 

 any species of insect uutil a sufficient acquaintance with its eco- 

 nomy is effected, and it is matter of much regret that, generally, 

 so little is known respecting the insects of this country ; a little 

 exertion, well directed, will do much in obtaining correct 

 information respecting them, and millions of dollars' worth of 

 property be saved to the agriculturist every year. 



Hoping that the zeal which has been so often displayed by the 

 coadjutors of the Institution, in other departments of science, 

 may be awakened in behalf of the important subject here pre- 

 sented, it makes this appeal, feeling assured that the assistance 

 so much needed will be freely afforded. 



JOSEPH HENRY, 



Secretary of the Smithsonian Institution. 



SMiTHSONiAif Institdtion, January 1, 1860. 



