REPORT ON INJURIOUS INSECTS FOR 1904 



Many growers have taken up and burnt infested stock and 

 planted clean, which, perhaps in the long run will prove the most 

 effective and the least expensive treatment. 



Further experiments on spraying and dusting with sulphur 

 are being carried out, the results of which will be given in a 

 future Report. 



THE BIRCH GALL MITE. 



Eriopliyes rudis (Canest.). 



Many examples of twigs of the Silver Birch infested with 

 this mite have been received. The so-called witches brooms can 

 be seen in mafiy plantations which a year or two ago were quite 

 free from them. In one case two fine trees had been practical!} 

 killed by this mite. A worse case than this I have not seen. 



FIG. II. LARGE WITCHES BROOM FORMED BY Eriophyes rudis. 

 From right to left the brcom measured just over a yard. 



My experience favours the view that this species is not one 

 that spreads rapidly, and if the clumps of aborted branches are 

 cut away and burnt as soon as observed, but very few mites 

 will be left behind, certainly not in sufficient numbers to do any 

 serious damage for some years. 



Dr. Buller informs me that according to Sadebeck there are 

 two fungi called Exoascus turgidus and E. bctulinus respectively, 

 which cause witches brooms on the Birch. Further Dr. W. G. 

 Smith! 1 ) has examined the brooms on the Birches in Scotland 



i. Tubeuf. Diseases of Plants. English ed., p. 160, Editor's Note. See also Dr. Fisher, Zeitschrf. 

 Pflanzenkr. 1901, Vol. xi. p. 321. 



