90 BRITISH OAK GALLS. 
Aphilothrix quadrilineatus, Hartig. 
(Plates XXV, XITI, div. C.) 
Andricus quadrilineatus, Hartig, Schenck, Mayr, Fitch, Cameron, 
Mosley; Aphilothriz quadrilineatus, Adler, Licht.; Cynips 4-lineatus, 
Thoms; Andricus flavicornis; A. ambiguus; A. verrucosus; A. 
peduncult; A. glabrusculus, Schenck.- 
English name of gall.—‘“ The Furrowed Catkin Gall.” 
Position of gall.—On the flower-stalk of staminate catkin. 
Manner of growth.—Sessile, glabrous, glossy; gregarious, 
longitudinally grooved. : 
Colours.—Pale green, greenish-yellow, reddish-brown. 
Average dimensions of a mature specimen.— Length, 
4mm.; breadth, 3 mm.; girth, 9 mm. 
May be sought during the months of May and June. 
Growth is complete by the end of June. 
The typical condition of the gall is unilocular and unilarval. 
The larva pupates in the gall. The imago emerges during the 
following spring. 
Parasites, Nos. 8, 66,154. Inquiline, No. 180. 
I have found as many as thirty-five of these galls 
on a catkin stalk measuring 70 mm. in length. 
The regularity with which the galls of this species 
appear on the same tree is remarkable. I have 
observed several trees, 80 to 150 years old, for the 
past fifteen years on which they have occurred each 
summer without intermission. Probably they were 
there many years before my observations began, and 
they will annually reappear until the trees are thrown, 
or they decay. 
This gall was first found in Britain by Professor 
Trail, in the year 1873, at Aberdeen. In the following 
summer EH. A. Fitch discovered it at Raleigh in Essex. 
It is now well known, and widely distributed all over 
the country. 
It appear to be more frequently found on Quercus 
pedunculata than on Q. sessiliflovu, and often itis on the 
same catkin as Spathegaster baccarum and Aphilothriv 
seminationts. 
It is subject to great variations in size, shape, and 
