20 THE OAK. 



The habitation of all the parasitic insects hitherto men- 

 tioned is formed out of the pulpy substance of the tree : 

 one, however, which is not uncommon, and is called the 

 Artichoke-gall, is an irregular development of the bud, and 

 consists of a number of leafy scales overlapping each other. 

 At first sight it might almost be taken for a young cone; 



ARTICHOKE-GALLS. 



but on dissection is found, like other galls, to contain insects 

 in various stages of their growth, according to the season. 



Another singular appendage of the leaf is the Oak- 

 spangle, a flat circular disc, attached by its central point 

 to the under surface of the leaf. The inner side is smooth; 

 the outer red, hairy, and fringed. Each of these contains 

 a single insect, which retains its habitation until March, 

 long after the leaves have fallen to the ground. 



Another insect of the same genus (Cynips) deposits its 

 eggs at the base of the trunk, immediately above the root. 

 In the early spring of the year, 1845, I detected two galls 

 formed by this species in Merthen Wood, Cornwall. The 

 larger was aboAit as big as a walnut, and produced in April 

 sixty small flies, much resembling winged ants. They were 

 not very active during their early existence, and possessed 

 the remarkable instinct, common to many other insects, of 

 counterfeiting death when touched. 



