1828

AHBORETUM AND FRUTICETUM.

PART ill-

varied in size: it did not, however, appear that they had eaten any part of theunder side of the excrescence. The larvae found beneath the excrescencewere destitute of legs, slightly hairy at the sides, and narrowed towards thehead : they were depressed and fleshy, with two points at the mouth and atthe extremity of the body : they were evidently the larvae of some dipterousinsect; and it does not appear that they had any actual connexion with theorigin of the excrescence in question. At the same time, lie opened some of thesame excrescences, which seemed younger, without pubescence, and of a greencolour, with the margins reflexed, and found in the centre a minute fleshywhite mass, of a thickened and curved form, and without any appearance ofarticulation, which he is inclined to regard as the young embryo of one ofthe Cynipidae. *

Other Insects found on the Oak. It still remains to notice the attachment ofseveral 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 forthe purpose of feeding upon the different insects which live on it. Thepurpie emperor butterfly (Apatiira I'ris Fabr.) belongs to the former class.The caterpillar of this most splendid of the English Lepidoptera feeds upontlie broad-leaved sallow; but the purple emperor himself “ invariably fixes histhrone upon the summit of a lofty oak, from the utmost sprigs of which, onsunny days, he performs his aerial excursions; and in these ascends to a muchgreater elevation than any other insect I have ever seen, sometimes mountinghigher than the eye can follow; especially if he happens to quarrel withanother emperor, the monarch of some neighbouring oak : they never meetwithout a battle, flying upwards all the while, and combating with each otheras much as possible; after which they will frequently return again to theidentical sprigs from which they ascended.” ( Haworth Lep. Brit., p. 19.) Ofthe latter class, the numerous tribes of /chneumonidae, C’halcididae, and otherparasitic Hymenoptera, which keep in check the hosts of oak-feeding cater-pillars, are especially to be mentioned; but it would be impossible to enterinto any detail of their individual habits, or to enumerate the species. Someof the lace-winged flies (Hemerobii) which feed upon the A'phides are also tobe found upon the oak; as well as their curious eggs, placed in clusters at theextremity of long and very slender footstalks, giving them the appearance ofminute fungi. Silpha 4-maculata, a coleopterous insect, also frequents theoak, in order to teed upon caterpillars; as do also splendid, but rare, speciesof Calosoma, C. inquisitor and C. sycophanta, the latter of which, both in thelarva and perfect state, is especially observed, on the Continent, to attack thelarvae of the processionary moths described above. M. Hose has observed(Diet. d’Agricult., art. Chene), and the observation affords an example ofmany admirable compensations so common in the economy of the animalkingdom, that this beetle is always more abundant in those seasons whenthe processionary caterpillars (which are extremely destructive to the oak)are also most abundant. ( Marquis, Essai sur les Harmonies Vegetales et Ani-males du Chene; Magas. Encyclop., 1814, tom. v.) Dr. H. Burmeister haspublished a valuable memoir upon the natural history and anatomy of thelarva of Calosoma sycophanta, in the first volume of the Transactions of theEntomological Society of London. *

Oak Barnacles. Among the many curious opinions entertained by theancients respecting the oak, those relating to the oak barnacle are, perhaps,the most extraordinary. The following quotation, from Professor Burnet’selaborate article on the oak in Burgess’s Eidodendron, contains some of thefables believed by the ancients Respecting them; and we shall add all that wehave been able to collect from other sources. “ The word bairnaacleis 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, byMr. W. Smith, giving an account of the discovery of winged specimens of a speciesof C^nips in theseoak spangles. It is not, however, until the month of March, and longafter Che oak leaves have fallento the ground, that the developement of the C^nips takes place, which accounts for the previousnon-observance of the economy of the species by which the spangles are produced.