1818

ARBORETUM AND FRUTICETUM.

PART III.

sanguineus. In the Magazine of Natural History (iv. p. 265.), Mr. Dale statesthat he found the latter insect “ in plenty, both in larva and pupa, on rottenoak stumps, in the New Forest. Tillus unifasciatus and ambulans also feed,in the larva state, on the rotten oak; and the latter was captured and bredby Mr. Dale. (See Mag. Nat. Hist., iv. p. 266.) But the most destructiveinsects to oak timber are the species of the family Lymexyldnidse, which,although common in Sweden and some other parts of the Continent, are,Fortunately, of great rarity in this country. Lymexylon dcrme stoides is abouti in. in length, and is found in the trunks of the oak, and some othertrees; whilst Lymexylon nasale Fab. (Cantharis navalisLinn., and our fig. 1646.) appears to be exclusivelyconfined to oak timber, which it perforates, and com-pletely destroys. ( Gyllenhal Ins. Suec., i. 317.) Sogreat, indeed, was the injury caused in the royal dock-yards of Sweden by this insect, that the greatest alarmwas entertained for the safety of the shipping; nor did itsubside until Linnceus, at the desire of the king of Sweden, had traced out thecause of the destruction; and had, having detected the lurking culprit underthe form of the beetle above mentioned, by directing the timber to be immersedduring the time of the metamorphosis of the insect and its season of oviposi-tion, furnished a remedy which effectually secured the wood from its futureattacks. (Smith’s Introduct. to Bot., pref., p. xv., quoted by Kirby mid SpenceIntr., i. p. 237.; Bechstein and Scharffenburg Forstins., vol. i.)

Tinea ramella Lin. feeds within the branches of the oak. (Syst. Nat., ii.p. 887.)

Insects which live under the Bark. There are also many species of insects(chiefly small Coleoptera) which reside beneath the bark of the oak, withoutboring into the solid wood. Of these, the Scdlytus pygmae'us, already alludedto in p. 1390., as having recently caused the destruction of 50,000 young oaksin the Bois de Vincennes, near Paris, is the most redoubtable. (Annales de laSoc. Entomol. de France, 1836, p. xxx.) Tdmicus villosus, I'ps 4-guttata,Hypulus quercinus, Cery Ion pilicorne, Rhyzdphagus dfspar, Silvanus uniden-tatus, and Bitoma crenata, are also subcortical beetles, the first-named speciesbeing one of the typographer beetles. (See Pinus.)

Insects which feed, on the Leaves. It is, however, upon the leaves of the oakthat the greatest proportion of its insect population finds its support; and itis chiefly amongst the caterpillars of lepidopterous insects that the greatestnumber of the leaf-feedersare found. Of these, theTortrix viridana Lin. (fig.

1647.), a very small, pretty,green species, is by far themost obnoxious; entirelystripping the oaks of theirfoliage, as we have more thanonce observed at CoombeWood, in Surrey. “ Eventhe smaller sorts of cater-pillars become, from theirmultiplicity, sometimes asdestructive as those whichare of considerable magni-tude. During the summer of 1827, we were told that an extraordinaryblight had suddenly destroyed the leaves of all the trees in the Oak ofHonour Wood, Kent. On going thither, we found the report but littleexaggerated; for, though it was in the leafy month of June, “there wasscarcely a leaf to be seen on the oak trees, which constitute the greaterportion of the wood. But we were rather surprised when we discovered, onexamination, that this extensive destruction had been effected by one of the

iiSiil’

S58H

1646