DIPLOSIS DRYOBIA. 147 
Diplosis dryobia, Léw. 
(Plate LXIII.) 
Diplosis Liebeli, Kieffer. 
Position of gall.—The margins of the lobes of the leaf. 
Manner of growth.—Glabrous, glossy, crescent-shape. 
Colours.—Pale green, green, light brown, dark brown, chocolate. 
Average dimensions of a mature specimen. — Length, 
15mm.; breadth, 2mm. 
May be sought during the months of June to September. 
Growth is complete by the end of July. 
The typical condition of the gall is unilocular but multilarval. 
Usual number of larve, 4. 
The larvz pupate in the ground. The imagines emerge 
during the spring. 
The margins of the lobes are curved upwards and 
folded down upon the upper surface of the blade, form- 
ing a thickened roll within which the larve live. The 
edge of the recurved portion presses very closely upon 
the surface of the leaf, preventing the intrusion of other 
small creatures, such as mites, etc., and retaining the 
larve until fully grown when it either gapes to allow 
them to fall to the ground, or they push their way out. 
The affected area is not easily noticeable from the other 
surface of the leaf. 
A species of Hriophyide, Hpitrimerus cristatus, 
Nalepa, a mite which occurs in Central Europe, 
causes the leaf-margins of Q. pubescens to curl in a 
similar manner; the folded portions, however, affect 
the under-surface of the leaf as well as continuing to 
the extremity of each indentation of the leaf. There 
is no change of colour in the rolled portions. 
It is probable that this species may be discovered in 
Britain. 
The dimensions of the mites are: male, 0°12 mm. 
long, 0°046 mm. broad ; the female, 0:17 mm. long, 
0°057 mm. broad. 
Plate LXIV is introduced from ‘ Zur Kenntniss der 
Gattung Trimerus,’ by the kind permission of Dr. 
Naepa, Vienna. 
