41 



less naturalized. Of the first I have said enough, but of the 

 second I would like to menti(^ a few interesting features. 



Insects differ so radically from each other, in habits as 

 well as in appearance, that i.t is not surprising that those 

 very elements, in the advance of civilization, that are the 

 most fatal to the existence of some species may have pre- 

 cisely the opposite effect upon another species. I have 

 never observed the larvae oi Dutana inter gerrima C. and R., 

 defoliate trees in the midst of forests, while the frecfuency 

 with which it strips the leaves from such walnut trees 

 as are planted, singly or in rows, along roadsides or on 

 lawns, shows that the abundance of these insects is much 

 influenced by this most commendable feature of refinement — 

 the planting out of this really beautiful tree for the purpose 

 of adornment. There has been a scourge of the grape de- 

 stroying insect, Fidia vilicida Walsh, during the last few 

 years along the shores of Lake Erie, and myriads of the in- 

 sect have been produced, where, under natural conditions, 

 very few could have developed. This is because there are 

 whole acres of vineyards where nature would have allowed 

 but very few vines to grow, and the disarrangement of af- 

 fairs by man has produced an over supply of the food plant 

 of this species. Other equally good illustrations might be 

 given. 



It is doubtless true that, but for the westward march of 

 civilization, the Colorado Potato Beetle, Doryfhora lo-lin- 

 cata Say, would have never occurred in Ohio. The pioneer 

 carried the potato with him, in his advance, until it reached 

 the home of this beetle, which adapted itself to this .sort of 

 food, and by the aid of this adaptation, pushed its way to 

 the Atlantic. Another, even more striking illustration of 

 the effects of adaptation, is found in Diahrotica longicorvis 

 Say. This insect probably occurs, in isolated localities, 

 from the Rocky Mountains to the Atlantic coast, and under 

 natural conditions, was, outside of such localities, not abund- 



