142 



The Galls of Essex ; a Contribution to a 



they do not become detached from the leaf. The gall-fly 

 emerges from the gall in October and November. Dkyophanta 

 DivisA, Hai'tig (Fig. 85) [agamous form of Spathegaster 



^'ERRUCOSA] . 



QuERcus RoBUR, L. Leaf. Galls very similar to those 

 last described are frequently fomid on the under side 

 of the oak leaf, but only singly, and they are not smooth, 

 but mostly covered with irregular nodules. In section 

 they also exhibit very thin walls to the larva-cell, and 

 are generally considerably smaller than the galls of 

 D. divisa, and are not so brightly coloured. The gall 

 is mature in early autumn, and the gall-flies emerge 

 therefrom in October. Dryophanta agama, Hartig (see 

 Fig. 35rt), sexual form unknown. 



QuERcusRoBUR, L. Leaf. The 

 common " silk button" galls oc- 

 cur in numbers on the under 

 side of the leaf, to which they 

 are attached by a very minute 

 foot-stalk; the gall is round, 

 with a depression in the centre, 

 and its surface is covered with Fig. 36. Neuroterm numismatis. 

 smooth, silky, brown hair ; hence 



its poj)ular name h-om its resemblance to a brown, silk- 

 covered button. When mature it has a diameter of about 

 the eighth of an inch ; it falls to the ground in the autumn, 

 and the larva feeds and grows in the single larva-cell 

 throughout the winter ; the gall-fly leaves the gall in March. 

 Neuroterus numismatis, Olivier (Fig. 36) [agamous form of 

 Spathegaster vesicatrix] . 



QuERcus RoBUR, L. Leaf. These galls occur in numbers 

 on the under side of the leaf as almost flat, circular discs, 

 yellowish in colour, but their upper surface is covered with 

 short, reddish-brown, stellate hairs. They are commonly 

 known as the " oak spangles." The galls fall from the leaf 

 in autumn. When mature they measure about one quarter 

 of an inch in diameter ; the larvpe feed and change to pupae 

 during winter, and the gall-flies emerge from the galls in 



