No. XV.B.] APPENDIX. 249 



ham, on Monday at Fulham, and on Tuesday at Tooting, on the turnip, 

 shepherd's-purse, and mallow. The green-fly is easily killed by the smoke 

 of tobacco ; the vastator, however, will live when the green-fly is destroyed, 

 and thus, in smoking greenhouses, the vastator is left when the green-fly is 

 killed. At the present time the vastator is to be found in nearly all green- 

 houses upon verbenas, and it kills them by wet gangrene in the same way 

 that it injures the potato plant. The vastator is remarkably destructive to 

 the potato and spinach plants, many less being required to kill them than 

 is required to destroy the beet or solani. I placed twelve potato plants in 

 a greenhouse in October for experiment : the vastator attacked them ; six 

 are now rotten, the other six are dying. One of the plants perishing from 

 the insect I have sent to the Polytechnic Institution, where every visitor 

 can see it. Perhaps there never was a series of minute observations made 

 on so large a tract of country as mine, upon this subject. I made observa- 

 tions over at least 400 square miles round London and Brighton, and 

 received specimens from the midland counties. I rejoice to find that a 

 knowledge of the insect is rapidly extending itself in all directions. Any 

 person may find it even now in their own gardens ; and as the spring 

 advances, it will be their duty to endeavour to exterminate it. 



Dec. 23, 1846. 



REAPPEARANCE OF THE APHIS VASTATOR UPON THE 

 POTATO PLANT. 



SIR, I regret to announce that the Aphis vastator reappeared last 

 week upon the potato plant in every district round London. At present 

 it may be found sparingly upon the under- surf ace of the leaf, and, though 

 within the last few days it has multiplied twenty-fold, several plants must 

 be examined before it can be detected. The present hot weather is highly 

 favourable to the rapid multiplication of this pest, which, coupled with its 

 early attack, must lead us to have the worst apprehension for the crops 

 this season. This creature has already greatly damaged the peach, apricot, 

 and nectarine trees in many localities. It is now feeding upon the turnip, 

 potato, and other plants. Allied species are destroying the currant tree, 

 and damaging to such a serious extent the carrot, parsnip, and parsley 

 crops, that they have exhibited in some instances the fatal plague spot 

 noticed in previous years upon the potato plant. These facts, unfor- 

 tunately, prove that in all human probability the great plague of aphides 

 will again run their destructive course this year. 



June 5, 1847. 



P.S. I shall be obliged for information and specimens of the aphis 

 from all parts of the country. 



