HOP-BLIGHT 319 



attacked by it within the hop-garden. If the infected 

 leaves are left to rot they carry on the parasitic fungus to 

 a new season. 



An interesting fact has been discovered about the hop- 

 blight aphis (called by zoologists Phorodon humuli). It 

 appears that the winter brood of this little insect (when the 

 hop-vine has died down) deposit their eggs on the bark 

 of the sloe (the wild plum), and also that any cultivated 

 plum trees serve them for the same purpose. When the 

 hop is dead they must of necessity get nourishment and 

 shelter from the plum tree. Clearly, then, if you can keep 

 all plum trees at a distance of half a mile from your hop- 

 garden you will render it very difficult, if not impossible, 

 for the blight aphis to carry on from season to season. It 

 will rarely, if ever, travel half a mile, and not in any 

 number. But hop-growers have not always the control of 

 the cultivation for half a mile around their hop-fields, 

 though large growers should be able to acquire it. The 

 skilful grower even finds it useful to leave one or two plum 

 trees in the hop-field, so as to attract the winter brood of 

 the blight aphis to them, and then he falls upon the 

 devastating but minute rascals with quassia and other 

 poisons, and ensures their destruction. The increase of 

 plum orchards in the neighbourhood of hop-gardens is 

 probably a chief cause of the increased loss by hop-blight 

 of late years in Kent. 



The hop-louse has other enemies besides the grower. 

 These are the lady-birds (less prettily called "lady-bugs"), 

 which feed greedily on the parasites, so that when the 

 hop-grower sees plenty of them on a hop-vine he does 

 not trouble to wash it. And there are other predaceous 

 insects which tend to keep the hop-lice down. Cultivation 

 and excessive production have resulted in putting, as it 

 were, too heavy a task upon the natural enemies of the 

 pest, whilst the more delicate but valuable varieties of 



