DAMAGE CAUSED BY ANIMALS. 147 



weather, or in April if it be less favourable, and deposits its eggs 

 under the bark of newly-felled stems or fuel-stacks arranged for sale, 

 or failing these attacks also standing trees of sickly growth, selecting 

 so far as possible only the portions of the tree where the bark is 

 thick. It also visits recently-formed Pine stumps for ovi-de- 

 position, and so long as such material is available it selects the 

 Scots Pine, or at anyrate the genus Pinus^ for the purpose, 

 although it may also occasionally be found on Spruce. 



The female insect generally effects an entrance at one of the 

 fissures of the bark, bores under the latter, and deposits the ova 

 along a vertical main gallery, which commences with a curve 

 before proceeding for a length of about 3'2 to 5*6 inches parallel 

 to the axis of the stem. Ovi-deposition is continued for about 

 3 to 4 weeks, up to 100 eggs being laid fairly close to each other in 

 niches or indentations along the edges of the main gallery. The 

 bore-holes, by means of which the insects effect an entrance, are 

 not infrequently noticeable from the yellowish outflow of resin on 

 the bark. 



The larvae eat sinuous galleries in the cambial layer of the 

 bark on each side of the main gallery, without boring into the 

 sapwood, and pass through the stage of chrysalides in pupal 

 chambers formed in the bark. The imago, of a brighter colour 

 at first than afterwards, appears as a rule in June, 11 to 12 weeks 

 after the laying of the eggs, or later if the spring weather has 

 been backward and unfavourable ; it bores its way out through 

 the bark for the purpose of at once proceeding to produce a 

 second generation. That a second generation could be produced 

 during the year, was formerly doubted by many; but recent 

 observations have proved that in mild situations such is the rule, 

 whilst in rawer and more unfavourable localities, where the 

 swarming in spring is usually a good deal later, only a single or 

 simple generation obtains. 



The beetles belonging to the second generation, often, too, 

 stragglers belonging to the first generation, that have been late of 

 developing, bore their way into the tops of the youngest shoots 

 just below the buds, and after eating the pith, either turn and 

 leave again by the entrance-hole or else from a special exit-hole. 

 The entrance-hole is generally noticeable by the formation of a 

 shell of resin round about it. Shoots, that have thus been 

 1 Weymouth Pines are often attacked and badly injured by this beetle. 



