THE CYNIPSWM. 



181 



considerable number of eggs. When the puncture is made the 

 insect spreads a secretion over the wound which is of a very 

 irritating character, and it is believed to excite the nutrition of 

 the vegetable tissue to develop irregular masses of its cellular 

 structures. There are multitudes of plants attacked, and generally 

 the shape of the gall differs in each, and is produced by a different 

 insect. Hartig, Westwood, Giraud, and others, have described 

 some very unusual forms. The oak trees afford a refuge for, and 

 nourish many kinds of gall-flies, which do not spare the trunks, 

 the leaves, the twigs, or the roots. Oak-apples, or the rounded 

 masses attached to oaks in the summer, some small and others 

 large, readily attract the attention ; they are galls that have been 

 pro'duced by a Cynips. They might be taken to be the fruit of 

 the oak, and they are to the eye miniature apples— oak apples. 

 The largest are always at the base of the leaves, and within them 

 there is a cavity tenanted by one larva ; it remains there in a dull 

 and stupid condition during the winter, and is transformed into 

 a pupa in the spring. The adult insect is developed within the 

 cellule, and is obliged to cut its way out into the world with its 

 mandibles. This Cynips is of a bright brown colour, and is called 

 Cynips qncrdts bacca^'wn. 



The small oak-apples that usually are found in plenty on the 

 lower surface of the leaves are formed by another species— Q/z/z/i- 



qnerctls folii. 



The branches of the oak in the spring-time are often covered 

 with nodules, some of which are very large and irregular in 

 shape. Their surface is smooth, their colour light green, passing 

 into red in some spots, and there are usually several on a twig 

 close to each other. They are constructed on a different plan to 

 those of the gall-leaf insects, for they contain twelve or fifteen 

 cellules, or more, each of which contains a larva. These kinds 

 of Cynips fly in the middle of the summer, and there are probably 

 two generations in each year. They are called Cynips terminalis, 

 on account of the peculiar ornamentation of the female. The 

 sexes differ much in their shape and colour ; the male has large 

 transparent wings, and its body is of a uniform bright fawn colour, 

 whilst the female has no wings whatever, and is brownish, the 

 end of the abdomen being of a shiny black tint. 



