108 FIRST ANNUAL REPORT OF 



once introduced, it would be a good plan to encircle a potato field 

 with a row of nettles, so as to concentrate the insects, and thus more 

 readily destroy them. It is also even more destructive to the egg- 

 plant than to the potato. Now, the egg-plant, the horse-nettle, and 

 the potato, all three of them belong to the same genus (Solarium), 

 as the wild plant upon which the larva originally fed in the Rocky 

 Mountain region; but the egg-plant and the horse-nettle are botani- 

 cally more closely related to the last than is the potato; being, like 

 the Rocky Mountain potato, covered with thorny prickles, while the 

 cultivated potato is perfectly smooth. On the other hand, the culti- 

 vated potato is much more nearly related to the Rocky Mountain 

 species than is the tomato; which last has, by modern botanists, been 

 removed from the genus to which the other two appertain, and placed 

 in a genus by itself. It would seem, therefore, that the closer a plant 

 comes to the natural lood-plant of the insect, the better the insect 

 likes it. 



The beetles have been sent to me, as taken from other plants, and 

 even from the raspberry, but I could never succeed in making them 

 feed on any plant that did not belong to the potato family, though I 

 am informed by my friend, Edgar Sanders, of Chicago, that they 

 greedily attack the tubers after they are dug, and he has found as 

 many as six in a single potato. 



It is undoubtedly a most singular and noteworthy fact that, out of 

 two such very closely allied species as the bogus and the true Colo- 

 rado Potato-beetles, feeding respectively in the first instance upon 

 very closely allied species of wild potato (Solatium rostratum and 

 S. carolinense), the former should have pertinaciously refused, 

 for about half a century, to acquire a taste for the cultivated 

 potato, with which it was all the time in the closest and most im- 

 mediate contact, while the latter acquired that taste as soon as ever 

 it was brought into contact with that plant. But, after all, this is not 

 so anomalous and inexplicable as the fact that the Apple-maggot Fly 

 ( Tnjpeta pomo?iella, Walsh), which exists both in Illinois, New York, 

 and New England, and the larva of which feeds in Illinois upon the 

 native haws, and has never once been noticed to attack the imported 

 apple there, should, within the last few years, have suddency fallen 

 upon the apple, both in New York and New England, and in many lo- 

 calities there, have become a more grievous foe to that fruit than 

 even the imported Apple-worm ( Oarpocapsa pomonella, Linn.)* 



Thinking that the bogus Colorado Potato-beetle might be com- 

 pelled to feed on the potato in a state of confinement, I gave it every 

 opportunity; but though the larva?, when transferred from the horse 

 nettle, fed more or less on potato leaves, they invariably became sickly 

 and eventually died. But even if they had actually fed upon potato 

 leaves quite freely in a state of confinement and developed into bee- 



* See on this subject the First Annual Report on the Noxious Insects of Illinois, hy Benj. D. 

 Walsh, pp. 29-30, in the Transactions of the Illinois State Horticultural Society for 1807. 



