90 BRITISH OAK GALLS. 



Aphilothrix quadrilineatus, Haitig. 

 (Plates XXV, XIII, diy. C.) 



Andricns quadrilineatus, Hartig, Sclienck, Mayr, Fitch, Caiiievou, 

 Mosley ; Aphilothrix quadriliiieatus, Adler, Liclit. ; Gtjnips ^-lineatus, 

 Tboins ; Audricus fiavicornis ; A. ainhiguus \ A. verrucosus; A. 

 ])edinu'u]i ; A. (jlahnisciiliis, Schenek. 



English name of gall. — " The Furrowed Catkin Gfall." 



Position of gall. — On tlie floAver-stalk of staminate catkin. 



Manner of growth. — Sessile, glabrous, glossy; gregarious, 

 longitudinally grooved. 



Colours. — Pale green, greenish-yellow, reddish-hrown. 



Average dimensions of a mature specimen. — Length. 

 4 nun. ; lireadth, o mm. ; girth, 9 mm. 



May be sought during the months of May and June. 



Growth is complete l)y the end of .Time. 



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. 130. 



I have found as many as tliirty-five of these galls 

 on a catkin stalk measuring 70 muL in length. 



The regularity with which the galls of this species 

 appear on the same tree is remarkable. I have 

 ol)served 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 Avill annually reappear until the trees are thrown, 

 or they decay. 



This o-all was first found in Britain by Professor 

 Trail, in the year 1873, at Aberdeen, In the followmg 

 summer E. A. Fitch discovered it at Raleigh in Essex. 

 It is now well known, and widely distril^uted all over 

 the country. 



It appear to be more frequently found on Quercus 

 2)efluncnJata than on Q. sessilijiora, and often it is on the 

 same catkin as Spafliegaster haccavum and Aj/liiloth-h' 

 seminationis . 



It is subject to great variations in size, shape, and 



