1826 



ARBORETUM AND FRUTICETUM. 



PART III. 



winged state, ready to take advantage of the first warm day to burst fortli 

 from their prison. This gall, which is the largest excrescence that we have 

 hitherto seen formed by any cyni()i(le()us insect, is irregularly oblong, and nearly 

 Fj in. in length : it is 1^ in. in diameter in the thickest \)avt, the general thickniiss 

 being about 1 in. : its ap[)carance is that of a i)ieceof very fine-grained sponge. 

 On making a section JTvin. long by 1 in. broad, between 60 and 70 cells, 

 closely packed together, and of an oval form, were discovered, each containing 

 a single cynips. Taking the size of the entire gall into consideration, it 

 must contain, at the lowest calculation, upwards of a thousand individuals, the 

 produce, probal)ly, of a single female cynips. The perfect insect is of a pale 

 brownish colour, with a shining red abdomen, having two small dorsal black spots 

 at the base. This gall was unknown to Keaumur, having been first described and 

 figured byBosc. (Jouni. de I'hysirjui;, 1794-.) A figure, apparently of the same 

 gall, is given in the Insect Architect., p. 385. ; but it is there erroneously 

 stated that the inhabitant is identical with the cynips of the oak apple (C. 

 quercus terminalis) ; and this is supposed to be accounted for by the observa- 

 tion, that the root galls are " probably formed at a season when the fly 

 perceives, instinctively, that the buds of the young branches are unfit for the 

 purpose of nidification." Numerous other excrescences, and some most 

 curious distortions, seem to be the result of the attacks of insects on the 

 buds or branches of the oak in their embryo or infant state, of which the 

 coadunate stems and witch knots are among the most remarkable ; but it is 

 doubtful whether many of these monstrosities are not idiopathic diseases of 

 the tree. 



The oak leaves, also, are occasionally observed covered with numerous 

 galls of small size, and evidently belonging to different species, being of dif- 

 ferent forms, of some of which the insect has not 

 yet been discovered. Several of them are figured 

 by Reaumur. {^Memoires, tom. iii. [)1. 3a. fig. 3, 

 4. and 6., pi. 40. f. 13—1.5.) Some of these 

 are of a larger size (fig. 1651.); not more than 

 three or four being found upon a single leaf 

 (Roscl Ins. Bel list. Siippl., tab. 69.) ; whilst 

 others, which are as large as a boy's marble, 

 and perfectly globular, are often found singly 

 upon the leaves ; the last being produced by C. 

 quercus folii. (Rcawn. j\Icm., tom. iii. pi. 39. 

 fig. 13—17., pi. 37. fig. 10, 11., pi. 40. fig. 8.) 

 It is a curious circumstance connected with 

 these large globular galls (and which is also 

 observed in the gall nut), that, notwithstanding 

 the large size of the galls, only a single insect is 

 enclosed therein; so that a very small portion 

 only of the centre of the gall is consumed, the 

 cynips arriving at its perfect state within its 

 small central prison, out of which it has to cut 

 its way through a great portion of the solid sub- 

 stance of the gall. The surface of the majority of these galls is smooth ; 

 some, however, are imbricated, and others are clothed with a woolly kind of 

 down, similar in its nature to the outside of the bedeguar of the rose. A gall 

 of this kind is figured in the Insect Arcli'itectnre, p. 388., found upon the twig of 

 an oak; and in Dr. Nees von Esenbeck's collection of minute Hymenoptera, 

 at present in Mr. Westwood's possession, there is a similar gall, of small size, 

 upon an oak leaf, with the cynips by which it is produced (C. quercus lanata 

 Nees MSS.). 



Oak Spannles. Amongst the excrescences found upon the leaves of the oak, 

 are to be noticed the reddish insular scales on the underside of the oak leaves 

 mentioned by Mr. Lowndes (Gard. Mag., vol. xi. p. 691.), and supposed by 

 him to be parasitic plants. When full grown, they are about one eighth of an 



