18 C 28 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 larvae 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 larvae 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 Cynipidae.* 



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 (Apatura Prb Fabr.) belongs to the former class. 

 The caterpillar of this most splendid of the English Lepidoptera 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 /chneumonidae, C'halcididae, 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 (Hemerobii) 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. $flpha 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 Continent, to attack the 

 larvae of the processionary moths described above. M. Bosc has observed 

 (Diet. d'Agricult., art. Chene"), 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 Vcgctales et Ani- 

 males du Chene ; Magas. Encyclop., 1814, torn, 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 Eidodendron, 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 Mnrcb, and longafter the oak leaves have fallen 

 to the ground, that the developement of the Cynips takes place, which accounts for the previous 

 non-observance of the economy of the species by which the spangles arc produced. 



