194 STATE HORTICULTURAL SOCIETY. 



It is not necessary to enter into the details of the architectural, 

 agricultural or military skill of these insects, nor even to enlarge upon 

 the striking and sigoificant analogies which their systems of labor, 

 government and provision for the future bear to the highest ideals on 

 these matters of the most favored races of men. These things are 

 more or less familiar to everyone, through either reading or observa- 

 tion, and I refer to them merely to recall them to memory, as illustrating 

 the manifestations of instinct in its highest development. If in any 

 insects, it would be in these that we would find absolute persistence 

 of habit, without variation and " without improvement in method." 

 But even in these, as I shall show, some remarkable, deviations, not 

 only in the selection of food, but in the line of economy of labor, have 

 been noted. Nor is instinct invariably dependable. The entomologist 

 frequently meets with instances of fatal error, and, as so small a pro- 

 portion of this class of animals comes under observation, we may infer 

 that these lapses are not at all uncommon. As the most unimportant 

 variation from ancestral habit serves to show that instinct is not the 

 fixed and automatic impulse that it is popularly considered, the follow- 

 ing instances are not without interest. 



Among the most common variations of habit are those of the 

 acquisition of new food material, whether of living plants or animals, 

 or of other substances. It is to this capacity for change from a few 

 widely scattered native plants to which a species has hithereto been 

 limited for its food supply, to the contiguous and comparatively luxuri- 

 ant products of our fields and gardens, that we owe the most serious of 

 our insect pests. The new injurious insects that are reported from 

 year to year are in most cases those that have been impelled by the 

 scarcity of their original food supply, or perhaps — (how can we tell) ? 

 to the experimental enterprise of some moth, or beetle, or locust — 

 to place her eggs upon some unaccustomed plant or substance — a habit 

 which outward circumstances would perpetuate in the generations im 

 mediately succeeding, until it was thoroughly implanted. As a rule, 

 such insects confine their attacks to plants of the same botanical family, 

 but in other cases, when they have once exceeded the limits of their 

 usual menu, they seem to cast aside all restrictions, and to put under 

 contribution an endless variety of vegetation. The European cabbage 

 butterfly illustrates this point. On the other side of the Atlantic, so 

 far as I can learn, it was not known to depredate upon any vegetation 

 outside of the family of the crucifers, and was seriously injurious to 

 but few of these. In this country, however, as though it had received 

 with emigrants of a higher order an impulse of freedom and enlarged 

 opportunity, it immediately began extending its list of food plants, not 



