Appendix. 507 



of friends appear, but as the damage has been done it is not much to 

 be thankful for. Next year we get just as bad an attack, if climatic 

 conditions have been favourable to the increase of the many which 

 escape their natural foes. 



The chief insects that we may call friends in Britain are the Lady- 

 birds (Coccinellidae), the Ichneumon and Chalcid Flies (Ichneumonidse, 

 Braconidse and Chalcididse), the Lace-wing or Golden Eye Flies (Chryso- 

 pidse), the Hover Flies (SyrpJiidse) and the Tachina Flies (Tachinidse), 

 some of which are shown in the figures given here. 



There have always been these parasitical and insectivorous insects ; 

 there have always been other insects causing endless loss to the fruit- 

 grower, and he knows full well in this country, where fruit-growing 

 knowledge is far in advance of any other, that they are no remedy for 

 such ills, and can scarcely be considered palliatives, and one can only 

 regret to see sums of money being wasted in such matters elsewhere. 

 Man must destroy his enemies, and it is useless to rely on Nature to do 

 so for him. 



C. WASHES AND FUMIGANTS USED AS INSECTICIDES 

 AND ACARICIDES. 



There are a great number of washes used for the purpose of destroying 

 insects, either acting directly or indirectly. Many of these have been 

 used in a haphazard way and have no scientific status. 



At present we know little about this subject, and it was not until the 

 Duke of Bedford and Mr. Spencer Pickering undertook the scientific 

 investigation of this important matter at Woburn that anything of 

 scientific and practical importance had been done. The result of their 

 work in a few years has been that the knowledge of insecticides in this 

 country has passed far ahead of that of America or any of our Colonies, 

 where previously we had to gain most of our knowledge. 



There may still have to be made some radical changes in the past 

 unscientific, but often very successful, treatment of this subject. For 

 instance, the writer at present cannot see, after twenty-five years' work, 

 that the metal emulsions are competent to deal with all caterpillars, but 

 further experiment may prove that, made with solar distillate, they are 

 just as useful as the more dangerous arsenical sprays. Even then we 

 may have to consider the injurious effects of paraffin on the health of 

 fruib trees as compared with the comparative harmlessness of arsenate 

 of lead. 



The importance of feuch vegetal insecticides as tobacco is one that we 

 must keep well to the fore, for after many years of experimenting and 

 observations, the writer has never seen, even when the trees are in 



