328 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Roughly speaking, we can divide the spraying for insects into two 

 groups, winter and spring spraying. I should like very much if I could 

 make growers think that there is a third, that is, spraying the trees, if 

 necessary, in the autumn. 



Why do we spray in the winter ? It appears from what I can gather 

 that the winter spraying is done for two purposes : the first is to cleanse 

 the trees, and the second to destroy the eggs of insects ; that is of course 

 prevention. As to cleansing the trees, that is a very desirable object. 

 Any dirty object wants cleansing to be brought into a more healthy 

 condition, and winter washing for the cleansing of fruit trees is certainly 

 an advisable, indeed a necessary, thing to do ; but what is the good of 

 winter washing to cleanse trees, as I too frequently see done, that are 

 normally clean ? It is a waste of money. You say it is done to destroy 

 the eggs of insects. A gentleman this morning said that he sprayed his 

 trees with Woburn wash, that is paraffin, caustic soda, and soft soap, and 

 the Psylla eggs were destroyed. The eggs of the apple Psylla, I am sorry 

 to say, so far as we can see generally, are not touched by the Woburn wash. 

 There is no winter wash which will burn through and corrode the eggs of 

 insects generally, such as, for instance, the winter moth or the lackey 

 moth. I have known people to say, " We can destroy these eggs with a 

 particular winter wash." Growers, I am sorry to say, gave up grease 

 banding ; they used winter washes, and the result has been that during 

 the past summer we have seen their trees devoid of leaves. We must 

 give up hope of destroying eggs of Psylla and most other insects until 

 someone comes along who will produce something so caustic that it will 

 burn through the shell of an egg (and I assure you it will have to be 

 very caustic) without harming the tree. If you take the egg of an 

 ordinary insect you have- to soak it in caustic soda before the shell is 

 destroyed ; that is a process you will have to adopt with your trees before 

 you corrode the eggs of the majority of insects. Possibly some other 

 means of killing eggs will be found, but none is known at present. 



The winter washes are therefore those you can use with a certain 

 amount of benefit if used properly where they are wanted for cleansing 

 the trees, and in so doing destroying the hibernating places of many 

 insects, and so in that way doing a certain amount of good. 



There are some, whose opinion we must certainly take account of, who 

 say that certain washes with paraffin in them will destroy a certain pro- 

 portion of insect eggs. Let us take a few examples. We will take, for 

 instance, the eggs of the apple aphis — the little black eggs you get on the 

 year's growth of wood. If you spray a tree with any winter wash con- 

 taining paraffin or carbolic you will find, if you look at the eggs, that a 

 very large number of them are shrunken up and destroyed. Then go to 

 a tree that is not sprayed and you will find exactly the same thing. They 

 are merely infertile eggs. And where people state that the eggs of insects 

 are destroyed by winter washes, I am quite certain that the destruction 

 which thoy think has taken place is merely the question of the infertility 

 of the eggs ; and if you examine the ova, no matter if of a hawk-moth or 

 any of the smaller insects, you frequently find as much as 50 per cent, of 

 them infertile ; and I believe where the mistake is made in winter washes 

 which are claimed to destroy a certain proportion of eggs is through not 



