34 
BRITISH GALLS 
Some of the galls caused by species in which the alterna¬ 
tion of generations occurs are delineated in Plates IV., V., 
and XXII. 
The first of these concerns the familiar “ Oak-apple.” If 
the reader visits a coppice in January, and carefully removes 
the earth from around some of the roots of an Oak, he may 
find upon them hard, brownish, spherical excrescences, 
ranging up to \ inch in diameter. All Oaks do not bear 
them, and perhaps considerable patience will have to be 
exercised before any are found. These galls may occur 
either singly or in large masses as seen in Plate IV., Fig. 5, 
but are never truly coalescent. If one of them is cut open, 
a yellowish-brown “ fly,” about 6 mm. long, will crawl out 
(Fig. 8). “Fly” is the term in general use, but it is not 
correct; the insect is a wasp, not a fly. Figs. 7 and 9 show 
respectively the gall and the insect, the latter magnified. 
This wasp is the Biorrhiza ciptera. It is always a female 
and always wingless. Her lot in life is not cast in easy 
lines. First of all she has to bore through the hard wall of 
the gall, next she has to push her way up through the earth 
and gain the trunk. Up this she crawls, a journey beset 
with a thousand perils. It is winter-time, and, wflth 
diminished food-supply, trunk-haunting birds, such as tits, 
nuthatches, and creepers, are maintaining a very vigorous 
search for insects of all kinds. Her quest is suitable 
terminal buds, in which she bores canals and deposits her 
eggs. Adler has given a vivid description of these boring 
operations, which differ from those of other gall-wasps. 
The necessary canals are first bored or pricked in the bud ; 
the eggs are pushed in afterwards. They are laid, not 
singly, but in hundreds, and their deposition requires time. 
“On January 27, 1878,” wrote Dr. Adler (I am quoting 
from Dr. Straton’s well-known translation), “ a fly was put 
upon a little oak, and soon began to prick a bud; when it 
had finished the first bud, it went on, without interruption, 
to another, and was altogether eighty-seven hours busily 
employed in laying its eggs. In these two buds I counted 
