TRIGONASPIS CRUSTALIS. 1389 
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. (= 54 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 by him in correspondence 
with Dr. Merrett in 1668 (see Introduction). 
Trigonaspis crustalis, Hartig. 
(Plates LVIII, LIX.) 
Cynips megaptera, Panzer; C. crustalis, Thoms.; Trigonaspis 
crustalis, Licht., Adler; TI. megaptera, Mayr, Walker, Marshall, 
Miller, Cameron; 7. renum, 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 during 
May and June. 
Parasites, Nos. 124, 162, 151, 16, 53. Inquilines, Nos. 129, 
130, 134, 189. 
Alternate agamic generation: Biorhiza renum, 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 
