284 THE WOODLANDS. 



WOOLLY OAK-GALL. Another gall is found on the 

 flower-stalk of the oak. It occurs on the male catkins, 

 in May, forming a mass as large as a horse-chestnut, 

 of a whitish colour, and woolly, something like a tuft 

 of sheep's wool. It has only rarely been found in 

 Britain, but has long been known on the Continent. 

 The little fly which causes it belongs to the same 

 genus, but is a different species from the foregoing. 1 



This does not exhaust the list of galls produced by 

 insects on oaks of different species, but it includes the 

 majority of those found in Britain. The Turkey 

 Galls, as they are called, are never found here, the 

 particular species of oak is not generally cultivated,, 

 and even the Turkey oak, which is not uncommon 

 in our parks, does not produce here the Knoppern 

 galls which are common upon it in Eastern Europe. 

 So few entomologists devote themselves to the special 

 study of galls that it is quite possible we may have 

 others which have hitherto escaped notice. If galls- 

 are collected before the larvae are well fed, the galls 

 become dry and shrivel, the maggots die, and con- 

 sequently the insect cannot be determined. 



ELM GALLS. Rarely galls are found upon the 

 branches of the elm, at the apex of the short lateral 

 twigs, and these attain a size from that of a walnut to 

 a large apple. These are hollow, and contain a con- 

 siderable quantity of fluid. They inclose an entire 

 colony of insects, of the aphis or plant-louse tribe, 

 and should more properly be termed cases than galls, 

 although they originate from a similar cause. The 

 insects are said to be a species of Eriosoma, and the 

 galls which they produce are common in Italy and 

 1 Cynips quercus ramuli. 



