3 $ 
BRITISH GALLS 
sap-supply, and these provide the requisite shield for the 
helpless larvae during the long months of winter. 
Oak galls are remarkably sporadic in their times of 
appearance. A gall may be very abundant one year, very 
scarce the next, and perhaps for many successive years. 
Of course, infrequency of the galls does not necessarily 
imply scarcity of the insects: they may have been as 
numerous as ever. In the case of spring forms, atmospheric 
conditions may retard the rise of the sap, and the larvae 
perish. Adler states that he was compelled to attribute to 
meteorological conditions a most important influence over 
the development of the egg. In 1904 the currant gall 
was extraordinarily abundant around Haslemere. I then 
recorded in my notebook that “ on nearly every Oak tree 
the male catkins are festooned with them, but here and 
there a tree may be found which, to all appearances, has 
entirely escaped attack. We always find exceptionally fine 
galls on Q. sessilijlora. The catkins which do not bear galls 
wither up and drop very quickly; the stalk of a galled one 
maintains its vitality for a considerable time.” The currant 
gall is well named. It appears in the latter part of May 
and early in June on the staminate flowers, and at maturity 
exactly resembles a red currant (Plate V., Fig. 1). 
Fig. 2 on Plate V. depicts a magnified section with 
the larval cavity. These galls grow with great rapidity. 
The wasps develop with equal rapidity, and by the end of 
June the majority will have left the galls. The wasp 
known as Neuroterus baccarum (Fig. 3) is about 4 mm. long ; 
the male has fifteen joints to each antenna, his partner one 
less. The galls also appear on the leaves, in which position 
they are larger, and green, never red. Barrett noted that 
the Tortrix Sciaphila communana lives in these galls. Many 
parasites have been bred from them. Rolfe found currant 
galls on nine species of Oak in the Quercetum at Kew. 
The female N. baccarum attacks the under surface of young 
Oak leaves, causing the well-known common spangle gall 
(Plate V., Fig. 4, a, a) to appear in July. These galls are 
