MITES AFFECTING THE POISON OAK 
325 
This mite is so abundant in certain places that every leaf on 
practically every plant is galled. Further, some of the leaves 
are so badly galled that they show general distortion and curl- 
ing. On the other hand a considerable area may be free from 
Fig. 52. Leaf of poison oak ( Rhus diver sitoba) showing galls produced by 
Phyilocoptes toxicopliagus n. sp. 
this mite. I have usually found it present in any large field 
where poison oak was growing, but not always. Plants badly 
infested are stunted and lack their normal vigor. 
