164 REPORT OF THE DEPARTMENT OF BOTANY OF THE 
FOOD PLANTS; CHARACTER OF INJURY. 
In Europe this species has been taken from the stems of Phlewm 
pratense, Poa pratensis, Agropyron repens, Festuca rubra, Des- 
champsia cacspitosa, Avena pubescens, Agrostis vulgaris, A. alba, 
Apera spica venti, Anthoxranthum odoratum and Alopecurus pra- 
tensis. In this country it has been collected from June grass (Poa 
pratensis), Phleum pratense, and in greenhouses from carnation 
buds. 
The work of the mite on grass and on carnations is quite dis- 
similar. On grass it attacks the succulent stem within the sheath 
just above the topmost node. According to Reuter the culm is 
first lacerated by the mandibles and then the plant juices are ex- 
tracted, causing the injured area to shrivel gradually and become 
twisted at or just above the node. The growth of the stem above 
this point is checked, causing the partially opened panicles to ripen 
prematurely and giving rise to the condition known as silver top. 
We have repeatedly examined grass stems for injuries of this 
character but have entirely failed to find conclusive evidence of 
the exact nature of the damage to our local grasses by the mite. 
The ‘initial injury is apparently not easily detected and in the gen- 
eral decline of the affected stem the wounds are apparently ob- 
scured and are not easily recognizable from the work of other 
agencies. In the early spring a decay of the injured portion of the 
stem is usually found. It always appears when the area attacked 
is close to the ground where the presence of moisture is fayor- 
able for its growth. This decay is due to the Sporotrichum pow 
before mentioned. The mites have been found breeding more 
freely under these conditions than upon the more exposed culm, 
On carnation plants the mite does not attack the stem but works 
into the center of the young buds. Here it introduces the same 
fungus with which it is associated on grass. Experiments made 
for the purpose of determining the point of attack indicate that the 
stamens or pistils are first attacked and later the less tender tissues. 
The fungus here finds a favorable condition for growth and in a 
comparatively short time the heart is entirely decayed and filled 
with mites while the growth of the buds is checked. 
