— 107 — 



brought into the laboratory for study, as soon as the leaves began 

 to dry, the mites left them and gathered in great numbers in the 

 buds. 



Means of Destroying the Mites. — Owing to the fact that the 

 mites live within the tissues of the leaves they are beyond the 

 reach of ordinary insecticides. It is obvious that they would not 

 be affected by any poison dusted or sprayed upon the surface of 

 the leaves. We conducted a series of experiments to ascertain if 

 the mites could be reached by an application of kerosine emulsion. 

 It was hoped that a sufficient quantity of the liquid would pass into 

 the galls through their open mouths to injuriously affect the mites. 

 But we obtained only negative results. Infested branches were 

 sprayed ; later when they were brought into the laboratory and 

 the leaves became dry the mites emerged from the galls in appar- 

 ently as great numbers as from branches that had not been sprayed. 



There seems to be only a single point at which the mite can be 

 attacked, this is in its winter quarters. As the mites collect in 

 the terminal buds in the autumn and remain there dnring the 

 winter, by carefully pruning and burning the 3'oung wood they 

 can be destroyed. This would be a simple matter in case of young 

 trees. But if the infested trees be large ones, the labor would be 

 considerable, still no one has been able as yet to suggest a less 

 laborious method. 



The pruning should be supplemented by a careful burning of 

 the fallen leaves and other rubbish in the orchard ; as some of the 

 mites being tardy in seeking their winter quarters in the buds may 

 be carried to the ground with the falling leaves. And as a last 

 precaution the trees should be examined soon after the leaves ap- 

 pear the following spring ; and if any of the leaves show the red- 

 ish spots characteristic of this disease, such leaves should be re- 

 moved and destroyed. It is probable that even with the most 

 careful pruning and burning a few mites will escape. But by de- 

 stroying them in the way indicated, as soon as they begin to form 

 galls, the cure will be complete. 



This is one of those cases where if it is worth while to do any- 

 thing it will pay to be very thorough. For if an infested orchard 

 be once freed from the pest, there is but little danger of its appear- 

 ing again, as the mites have very limited powers of spreading. 



