No. XV.B.] APPENDIX. 251 



potatoes may be frequently observed to be covered with, a white down, 

 which in reality is a beautiful appearance of the Botrytis infectans. In 

 consequence of these appearances following the attack of the aphis, hasty 

 investigators are sometimes led to the belief that the potato disease occurs 

 without the insect a delusion now highly prized by those who admire the 

 marvellous, and delight to speculate in aerial, comet, and cholera theories. 



The early kinds of potatoes are now, in most instances, ripening to 

 satisfaction, and the golden yellow colour of the foliage demonstrates that 

 the leaf is performing its last functions, and that the tuber is being well 

 filled with starch and other nutritive matters. The late kinds still look 

 well, and scarce any insects now exist in many situations. The agricul- 

 turist should not, however, trust too much to the pleasing intelligence, for 

 he should be aware that they may again return between this time and 

 November, and eat down his crop. The large flights of vastators last 

 year occurred between the 7th of September and the end of the month. 

 These remarks are quite independent of some local instances where the 

 disease has committed ravages to a great extent. I have heard of one 

 field which yielded 17 sacks of bad and 32 of good tubers, and doubtless 

 there are many other like cases, but they now form rather the exception 

 than the rule. I have myself nearly 200 kinds of potatoes planted in 

 ground without manure, and I do not think amongst the number that I 

 will find a single diseased tuber. 



Carrots and parsnips, which have been infested all the season, are now 

 comparatively free ; and the damage has not been so great as to prevent 

 their perfect recovery. 



We rejoice also to state that the corn aphis, which was disseminated 

 over every part of the country, even to a few seedling oats growing in a 

 vacant piece of ground opposite the Royal Exchange, is now diminishing, 

 or even, in many localities, has disappeared. Its effect was to injure the 

 produce, and cause black marks to appear upon the ear and stem. It 

 came too late to effect extensive damage in this country. Private letters 

 from Baltimore state that the wheat and potato crops are abundant, and 

 that the former has dropped in price to one -half its highest rate last year. 



At the commencement of the season I called attention to the reappear- 

 ance of the Aphis vastator. During the progress of the year I have 

 pointed out the damage which various aphides have committed. Now I 

 have to communicate the singular and welcome fact of their extensive and 

 sudden departure. The past has afforded no indication for the present, 

 nor can the present indicate the future. Before this article is distributed 

 over the country, the aphides may recur; and, though I now write to 

 congratulate the farmer on his present prospects, I must yet caution him 

 to be continually on the watch, so that he may immediately discover if 

 another plague of these all-destroying creatures should visit his crops. By 

 correct information on these points, arrangements can be made before- 

 hand ; and cheap food, one of the greatest of all desiderata, may be 

 secured for the people. 



FlNSBTJRY CIRCUS, ALFRED SMEE. 



Aug. 5, 1847. 



