24 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



The number of insect enemies that the fruit-grower in this country has 

 to contend with amounts to over one hundred. Many of these are local, 

 however, and others only occur now and again, such as the Cherry-tree 

 Borer (Se?nasia woeberana) in a few orchards in Kent, the,. Pear-leaf 

 Miner (Cemiostoma scitella) in parts of Scotland, the Cherry-bud Moth 

 (Gelechia nanella), the Social Pear Sawfly (Pamphilus flaviventris) in 

 the south of Britain, and the Strawberry Aphis (Siphonophora fragarice) 

 in Herefordshire. 



All these and the others are of interest and importance, but it would 

 not be possible to even refer to them to-day. 



I am thankful to say Mr. Warburton is going to especially deal 

 with two enemies, namely, the Big Bud in Currants and the Pear Midge. 



I should like, if I may, to limit my remarks to the treatment more 

 than the life-history of some of the fruit pests, except where special points 

 in their development call for comment ; besides, the life-histories of our 

 worst enemies are well known to us all. 



The most harmful insect pests of fruit are undoubtedly the following : 

 the Mussel Scale (Mytilaspis pomorum), the Apple-sucker (Psylla mali), 

 a number of plant lice (Aphididce), the Winter Moth, the Tortrices, and 

 the Codling Moth (Carpocapsa pomonella), the Apple-blossom Weevil 

 (Anthonomus pomorum), and the Currant Sawfly (Nematus ribesii), 

 together with the Pear Midge (Diplosis pyrivora) and the Currant Gall 

 Mite (Eriophyes ribis). 



The Mussel Scale. — The presence of this scale, now found wherever 

 Apples and Pears are grown, is not always readily detected when present 

 in small numbers, unless the trees are carefully examined. This is 

 owing to the fact that the scale covering the insect assumes the colour of 

 the bark during most of its existence. No notice is taken when it occurs 

 in small numbers, for then it does no harm. We must not forget, how- 

 ever, that all insect and fungoid enemies may suddenly increase. What 

 regulates this plethora of life we do not always know. Some say it is 

 due to the scarcity of natural enemies. The Mussel Scale is preyed 

 upon by minute parasites — Chalcid flies — and by birds such as the blue 

 tit, tree creeper, gold-crested wren, and nuthatch. 



Chalcid parasites occur in most districts, but I have never yet seen 

 them in sufficient numbers to hold the scale in check, and in some cases 

 I have seen the Coccid increase in spite of the Chalcids in such enormous 

 numbers that the very existence of the trees has been threatened. Nor are- 

 birds capable of holding the foe at bay. On the other hand, I think we 

 shall find that many pests are spread by our feathered friends ! 



W T e must, therefore, adopt remedies and not only rely on nature to 

 provide an antidote. 



Treatment. — The treatment of the Mussel Scale is best carried out by 

 spraying, unless the attack is very severe, and then nothing but scrubbing 

 will do any good. 



A series of experiments conducted during the past two years has 

 shown that several previously supposed remedies are of little avail. 



Caustic wash is of very slight use, as it has little penetrative pro- 

 perties and so does not soak under the scales, and get to the eggs, when 

 we apply it during the winter months. Nor can we use it at sufficient 



