TRIGONASPIS CRUSTALIS. 139 



it will remain in a lightly attached manner for several 

 days. Expansion of the surface of the gall ultimately 

 causes it to fall. 



The growth of the gall is rapid, and does not cease 

 until it has attained, in some specimens, a girth of 

 134 mm. (= 5J inches), and even larger. Although 

 generally solitary in mode of growth, as many as five 

 are sometimes crowded together. When mature, 

 suffused with pink or madder, and surrounded by 

 several leaves this gall is among the most charming 

 of those on the British oaks. 



This gall was observed in England by Sir Thomas 

 Browne, and mentioned b}^ him in correspondence 

 with Dr. Merrett in 1668 (see Introduction). 



Trigonaspis crustalis, Hartjg. 

 (Plates LVIII, LIX.) 



Cynips megaptera, Panzer ; C. criistalis, Tlioins. ; Trigonaspis 

 crustalis, Licht., Adler ; T. megaptera, Mayr, Walker, Marshall, 

 Miiller, Cameron; T. renvin, Mayr. 



English name of gall. — "The Pink Wax Gall." 



Position of gall. — Low down on bark of trunk, and small twigs 

 growing therefrom. 



Manner of growth. — Single, glossy, glabrous, gregarious, 

 globular, succulent . 



Colours. — White, cream, greenish -yellow, pink, red, reddish- 

 brown. 



Average dimensions of a mature specimen. — Girth, 30 mm. 



May be sought during the months of April to June. 



Growth is complete by the end of May. 



The typical condition of the gall is unilocular and unilarval. 



The larva pupates in the gall. The imago emerges dm-ing 

 May and June. 



Parasites, Nos. 124, 162, 151, 16, 53. Inquilines, Nos. 129, 

 130, 134, 139. 



Alternate agamic generation : Biorhiza remivi, Hartig. 



This gall was well known in England many years 

 prior to 1874. 



It is unusually succulent. The tissues are very 

 fully charged with an acerb, cloudy fluid of which as 



