1828 ARBORETUM AND FRUTICETUM. PART III 
varied in size: it did not, however, appear that they had eaten any part of the 
under side of the excrescence. The larva found beneath the excrescence 
were destitute of legs, slightly hairy at the sides, and narrowed towards the 
head: they were depressed and fleshy, with two points at the mouth and at 
the extremity of the body : they were evidently the larva of some dipterous 
insect ; and it does not appear that they had any actual connexion with the 
origin of the excrescence in question. At the same time, he opened some of the 
same excrescences, which seemed younger, without pubescence, and of a green 
colour, with the margins reflexed, and found in the centre a minute fleshy 
white mass, of a thickened and curved form, and without any appearance of 
articulation, which he is inclined to regard as the young embryo of one of 
the Cynipide. * 
Other Insects found on the Oak. It still remains to notice the attachment of 
several species of insects to the oak, which do not obtain subsistence therefrom, 
but take up their abode either from some partiality to the tree itself, or for 
the purpose of feeding upon the different insects which live on it. The 
purple emperor butterfly (Apatira I‘ris Fabr.) belongs to the former class. 
The caterpillar of this most splendid of the English Lepidéptera feeds upon 
the broad-leaved sallow ; but the purple emperor himself “ invariably fixes his 
throne upon the summit of a lofty oak, from the utmost sprigs of which, on 
sunny days, he performs his aerial excursions ; and in these ascends to a much 
greater elevation than any other insect I have ever seen, sometimes mounting 
higher than the eye can follow; especially if he happens to quarrel with 
another emperor, the monarch of some neighbouring oak : they never meet 
without a battle, flying upwards all the while, and combating with each other 
as much as possible; after which they will frequently return again to the 
identical sprigs from which they ascended.” (Haworth Lep. Brit., p. 19.) Of 
the latter class, the numerous tribes of Jchneuménide, Chalcidida, and other 
parasitic Hymenoptera, which keep in check the hosts of oak-feeding cater- 
pillars, are especially to be mentioned; but it would be impossible to enter 
into any detail of their individual habits, or to enumerate the species. Some 
of the lace-winged flies (Hemerdbii) which feed upon the A’phides are also to 
be found upon the oak ; as well as their curious eggs, placed in clusters at the 
extremity of long and very slender footstalks, giving them the appearance of 
minute fungi. Silpha 4-maculata, a coleopterous insect, also frequents the 
oak, in order to feed upon caterpillars; as do also splendid, but rare, species 
of Calosoma, C. inquisitor and C. sycophanta, the latter of which, both in the 
larva and perfect state, is especially observed, on the Continest, to attack the 
larvee of the processionary moths described above. M. Bosc has observed 
(Dict. d@ Agricult., art. Chéne), and the observation affords an example ‘of 
many admirable compensations so common in the economy of the animal 
kingdom, that this beetle is always more abundant in those seasons when 
the processionary caterpillars (which are extremely destructive to’ the oak) 
are also most abundant. (Marquis, Essai sur les Harmonies Végétales et Ani- 
males du Chéne; Magas. Encyclop., 1814, tom. v.) Dr. H. Burmeister has 
published a valuable memoir upon the natural history and anatomy of the 
larva of Calosoma sycophanta, in the first volume of the Transactions of the 
Entomological Society of London. * 
Oak Barnacles. Among the many curious opinions entertained by the 
ancients respecting the oak, those relating to the oak barnacle are, perhaps, 
the most extraordinary. The following quotation, from Professor Burnet’s 
elaborate article on the oak in Burgess’s Hidodendron, contains some of the 
fables believed by the ancients respecting them; and we shall add all that we 
have been able to collect from other sources. ‘ The word bairnaacle 
is from bairn, a child or offspring, and aacle or acle, the aac, or oak; 
signifying the child or offspring of the oak. Munster, in his Cosmography, 
: 
% Since this sheet was prepared for press, a memoir has been read at the Entomological Society, by 
Mr. W. Smith, giving an account of the discovery of winged specimens of a species of Cynips in these 
oak spangles. It is not, however, until the month of March, and longafter the oak leaves have fallen 
to the ground, that the developement of the Cynips takes place, which accounts for the previous 
non-obser vance of the economy of the species by which the spangles are produced. 
