1818 



ARBORETUM AND FRUTICETUM. 



PART III. 



sangiifneus. In the Magazine of Natural History (iv. p. 265.), Mr. Dale states 

 that he found the latter insect "in plenty, both in larva and pupa, on rotten 

 oak stumps, in tlie New Forest. Tillus unifasciatus and Smbulans also feed, 

 in the larva state, on the rotten oak ; and the latter was captured and bred 

 by Mr. Dale. (See Mng. Nat. Hist., iv. p. 260.) But the most destructive 

 insects to oak timber are the species of the family Lymexyl6nidae, which, 

 although common in Sweden and some other parts of the Continent, are, 

 fortunately, of great rarity in this country. Lymexylon (/ermestciides is about 

 i in. in length, and is found in the trunks of the oak, and some other 

 trees; whilst Lymexylon nasiile Fah. (6'antharis navalis 

 Linn., and our Jig. IG-tG.) appears to be exclusively 

 confined to oak timber, which it perforates, and com- 

 pletely destroys. (Gi/l/en/iat Ins. Snec, i. 317.) So 

 great, indeed, was the injury caused in the royal dock- 

 yards of Sweden by this insect, that the greatest alarm 

 was entertained for the safety of the shipping; nor did it 1646 



subside until Linnaeus, at the desire of the king of Sweden, had traced out the 

 cause of the destruction ; and had, having detected the lurking culprit under 

 the form of the beetle above mentioned, by directing the timber to be immersed 

 during the time of the metamorphosis of the insect and its season of oviposi- 

 tion, furnished a remedy which effectually secured the wood from its future 

 •attacks. (Smithes Introduct. to Bot.,pre{., p. xv., quoted hy Kirbi/ and Spcncc 

 Intr., i. p. 237. ; licchstein and Schaiffenburg Forsiins., 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, without 

 boring into the solid wood. Of these, the Scolytus pygmse^us, already alluded 

 to in p. 1390., as having recently caused the destruction of .50,000 young oaks 

 in the Bois de Vincennes, near Paris, is the most redoubtable. (Amiales de la 

 Soc. Entomol. de France, 1836, p. xxx.) Tomicus villosus, /'ps 4-guttata, 

 Hypulus quercinus, Cerylon pilicorne, Rhyzophagus dfspar, Silvanus uniden- 

 tatus, and Bitoma crenata, are also subcortical beetles, the first-named species 

 being one of the typographer beetles. (See Pinus.) 



Insects which Jeed on the Leaves. It is, however, upon the leaves of the oak 

 that the greatest proportion of its insect population finds its support ; and it 

 is chiefly amongst the caterpillars of lepidopterous insects that the greatest 

 number of the leaf-feeders 

 are found. Of these, the 

 Tortrix viridana Lin. (Jig. 

 \ 647.), a very small, pretty, 

 green species, is by far the 

 most obnoxious ; entirely 

 stripping the oaks of their 

 foliage, as we have more than 

 once observed at Coombe 

 Wood, in Surrey. " Even 

 the smaller sorts of cater- 

 pillars become, from their 

 multiplicity, sometimes as 

 destructive as those which 

 are of considerable magni- 

 tude. During the summer of 1827, we were told tliat an extraordinary 

 blight had suddenly destroyed the leaves of all the trees in the Oak of 

 Honour Wood, Kent. On going thither, we found the report but little 

 exaggerated ; for, though it was in the leafy month of June, " there was 

 scarcely a leaf to be seen on the oak trees, which constitute the greater 

 portion of the wood. But we were rather surprised when we discovered, on 

 examination, that this extensive destruction had been effected bv one of the 



1647 



