26 YALE AGRICULTURAL LECTURES. 



An insect may be known to be in its perfect or mature state 

 when it has wings ; or if it be a wingles variety its maturity is 

 known by its depositing eggs. In grasshoppers, plant-bugs, 

 and leaf-hoppers, the changes are less complete, they never 

 having the form of a worm, the young resembling the mature 

 insect, only being smaller and without wings. 



Insects, however much we may despise them, have a real use 

 in the domain of nature destroying all that is dead, and check 

 ing the increase of all that is living in the vegetable world. 

 Without them the earth would immediately be overrun with 

 plant life. And hence those trees and plants which it is man's 

 object to cultivate, come to be attacked by those insects whose 

 office it is to repress these kinds of vegetation. To be success 

 ful in his labors, therefore, man is obliged to combat those 

 insects which thus prey upon his crop. To do this he must 

 study their habits and transformations. 



Dr. Fitch closed by stating, that the more he examined these 

 creatures, the more confimed he became in the opinion, that 

 there is no injurious insect but that, when we become ac 

 quainted with all the details of its history and habits, we shall 

 be able to detect some assailable point and devise some meas 

 ure by which either the insect can be destroyed or the vegeta 

 tion can be shielded from its attacks. We shall discover that, 

 although he may be invulnerable in every other part, no nsgis 

 protects his heel, and if we strike Achilles there, we inflict a 

 death wound. A prolonged outburst of applause, on the close 

 of the lecture, attested how deeply Dr. Fitch had interested 

 the audience. 



Subsequently, in confirmation of Dr. Fitch's statement, that 

 it was not a deterioration of the soil nor change of our climate 

 that prevented our growing such crops of wheat now as for 

 merly, but was the insect enemies of this grain with which the 

 country has become overrun, a gentleman from Maine reported 

 that in a remote part of that State, where a district has recently 

 been newly cleared, distant from where wheat has ever been 



