PREFACE. 



in Derbyshii-e and Hampshire had both lost over £100 in 

 one season on this crop alone ; and that the losses to hop- 

 growers due to the hop aphis have been incalculable. 

 In the last serious blight in 1882, the whole produce of 

 the hop lands in England— 65,619 acres— did not exceed 

 114,832 cwts., or a yield of If cwt. per acre." For 

 comparison, it may be stated that on an average the 

 English hop lands yield about 7 cwts. per acre. 



As an instance of the losses caused hy fungoid pests, we 

 may allude to the much-dreaded Peronospora infestans. 

 There is no doubt that " the potato disease in a bad year 

 affects the whole community ; but it falls with crushing 

 force upon the large growers, for the potato is always 

 an expensive crop. The amount paid away in 1880 in 

 consequence of the failure of the preceding year, was 

 £2,847,027. Yet in 1885, after a smaller area by 18,987 

 acres, £727,806 sufficed to make good our requirements. 

 This enormous difference of £2,119,221 roughly indicates 

 the loss sustained by home potato-growers in 1879 ; and 

 that season had been preceded by several other scarcely 

 less calamitous years." 



Therefore nothing more need be said of the practical 

 utility of the subject discussed in the following pages. 



The main object of this volume is to detail, in a concise 

 form, the life-histories of the principal insect and vege- 

 table foes of the farm, and to give an account of the 

 means for destroying them or preventing their attacks. 



The microscope being of such practical utility for the 

 proper study of parasitic fungi and insects (and especially 

 the former), a short chapter has been added concerning 

 its use as a means of examining and studying the various 

 parasitic fungi and insects detailed in the present volume. 

 In my opinion, the best objectives are those made by Zeiss 



