154 LETTERS TO MR. WISE [CHAP. xvi. 



the trees last year, and I have every prospect of securing a 

 good half crop. Our neighbour's trees in this village are 

 utterly ruined, scarcely a leaf to be seen, and the trees 

 completely covered with the affected knobs." 



But with regard to the life history of the pest, I believe it 

 breeds entirely in the infested buds, and I believe also 

 breeds, i.e., lays eggs, there at any time during the winter. 

 I know that the nearly allied nut-Phytoptus does, for I 

 have seen them. Outside the buds, so far as I know, the 

 life is wholly spent in sheltering in crannies or straying 

 about, on the stems, or on the ground. What we want, 

 appears to me to be, to clear the mite by syringings from 

 the stems when the buds (of which we have now the galled 

 growth) are first beginning to form. But I do not see how 

 we could do this, for we should ruin the fruit. My only 

 hope for real prevention where black-currants are grown 

 on this large scale, is in an alteration of the method of 

 cultivation. As it stands now, the mites can convey them- 

 selves, or be carried by wind-borne leaves, or may creep 

 from one bush to another on the ground, but if there 

 could be a mixing of some field crop in strips with the 

 black-currants, I believe it would do a deal preventively. 

 If the ground between the rows were occupied by some 

 crop that the Phytopti \vould not pass, it could not fail to 

 lessen their presence. Even strips of strawberries or of 

 gooseberries would be beneficial. I wonder whether 

 kainite would be a good remedial application ? It might 

 kill all the mites that are about, but it is quite plain to 

 me that, as nothing that has been tried for so many years 

 answers thoroughly, we are on the wrong lines and need 

 a new plan. I wish you would, at your leisure, tell me 

 what you think of mixing crops, and if you could let me 

 have just a few little bits of galled twigs for figuring, I 

 should be very much obliged. I wish I could help better 

 about the matter, but so far the attack appears to have fairly 

 baffled us all. 



April 13, 1897. 



I am very much obliged for these remarkably fine speci- 

 mens of Currant galls, which reached me safely this morn- 

 ing. About the life history of the Phytopti, I do not think 

 that anything more is recorded than what both you and I 

 know. But as we know well that the mites are in the galls 

 (such as you send me), it seems to me that what we have got 

 to act upon is their condition (or locality, rather) in the time 

 between their leaving these galls and when they are starting 



