CHAP. CIII.

■SALICa'cE/E. a’a'lix.

1481

Baxter, several of the species are in some seasons almost entirely destroyedby the Cryptorhynchus lapathi. Mr. Baxter, jun., informs us that the species ofwillow which are least injured by this insect are, the S. pentandra, S. deci-piens, and S. nigricans. After the wood in the trunk of the tree is partiallydestroyed, it is generally found infested by the black ant (Formica fuliginosaLatr.), which is found, not only in the wood of the willow, but in that of otherdecayed trees, even in houses, living on the decayed rafters and woodenfloors. In Kirby and Spence’s Entomology, these insects are described as livingin societies, and “ making their habitations in the trunks of old oak or willowtrees, gnawing the wood into numberless stories, more or less horizontal, theceilings and floors of which are about five or six lines asunder, black, and asthin as card; sometimes supported by vertical partitions, forming an infinity ofapartments, which communicate in some places by small apertures; and atothers by light, cylindrical pillars, furnished with a base and capital, which arearrayed in colonnades, leaving a communication perfectly free throughout thewhole extent of the story.” ( Kirby and Spence’s Introd., &c., i. p. 483.)

By far the most valuable species of willow in English woods, as alreadystated, is S. caprea; and on this the Trochilium crabroniforme, or lunar hornetsphinx, feeds, in its larva state, upon the living wood, by boring into the trunk,and thus destroying the tree. An account of this insect has been communicatedto the Magazine of Natural History by the Rev. W. T. Bree, of which we give theMowing abstract ; —“In the Transactions of the Linnwan Society, vol.iii. tab.i., afigure of the Tro-chilium crabroni- 1290

forme (fig. 1290.),under the nameof Sphinx crabro-niformis, is givenin its three stages.

Lewin, the writerof the article,gives it as hisopinion that ‘ thecaterpillar doesnot enter the

wood till the second year of its own age; ’ and he states as a reason, that,‘among all the numerous larvae he has found from June to November, hecould perceive but a slight difference in size. Possibly, therefore, they mayfeed on the tender bark of the sallow root the first year after they arehatched.’ ” This, Mr. Bree thinks, is very probably the case; for he adds thathe has not observed in the wood any perforations of a very small size, orsuch as have the appearance of having been made by caterpillars newlyhatched. As the caterpillar eats its way upwards through the solid wood, aquestion may arise: How is the sphinx, when it bursts from the chrysalis,to make its escape out of the wood without injury ? To obviate this diffi-culty, instinct directs the caterpillar, before it changes to a chrysalis, to turnits head downwards, so as to be opposite to the orifice, which affords a readyexit for the winged insect. A portion of the plate in the Linncean Transac-tions above referred to is copied in Jig. 1290.; in which a is the male imago,or perfect insect ; b, the female imago: and in fig. 1291.; in which c is the larva,or caterpillar, in its proper situation, with its head upwards, in the act of feedingon the wood; d, the pupa, with its head downwards, preparatory to its exit;T e ’ *'^ le we k olosiog the orifice by which the larva had entered, and by whichthe imago must come out. Mr. Bree sent us the butt ends of three young willowtrees, which had been perforated by the insect, as shown by a view of their endsgiven mfig. 1292. One of these, on being split up, presented the appearance offig- 1292. a; and, as it did not then include the case of the pupa, we concludethat the insect had escaped. The insect enters the stems, which it perforatesnear theroot, and eats its way up wards for several inches, sometimes to thelength