379 



The black pine beetle, Hylastes aler, and the brown pine beetle, 

 Hylastes [Hylurgops) palliatiis, have already been noticed [R.A.E., A, 

 vi, 116]. The former can only be controlled by uprooting and burning 

 all attacked plants and trapping the beetles by means of thin 

 logs partly buried in the soil on the slant. Other beetles of the genus 

 Hylastes cause injury to a minor degree. H. palliatus causes damage 

 by boring under the bark of sickly trees, and by the borings of the 

 larva. Control depends almost entirely on clean forestry methods, as 

 trap- trees do not always prove attractive. 



The two-toothed pine beetles, Pityogenes hidentatus, and in the north 

 of Scotland P. quadridens, destroy the cambium in cutting their egg- 

 tunnels under the bark. As they are very prolific where they occur, 

 they rapidly encircle young stems, causing cessation of the sap flow 

 and death. The eggs of the first brood are laid in May, and of the 

 second in August and September, and in the extreme north even in 

 October in mild weather. The best remedial measures consist in 

 burning all slash and the destruction of attacked plants. Where the 

 infested stems may be saleable as stakes, the bark should be removed 

 and burnt. Owing to the usual density of the plantations attacked, 

 the use of trap-trees is not always practicable. Plants from five to 

 twenty-five years of age are attacked, and occasionally nursery plants. 



The large-toothed pine beetles, Ips {Tomicus) laricis and /. (T.) 

 amiminatus, have greatly increased in numbers of recent years. Their 

 life-history under British conditions is not known ; clean forestry 

 methods and the burning of all slash are the best means of dealing with 

 them. The pith pine beetles, Pityophthorxs lichtensteini and 

 P. ■pihescens, are of little importance except locally in Perthshire. 

 They tunnel in the bark and pith of the smaller pine twigs. 



Insects associated with felled spruce areas are not in general of such 

 great importance. They include Hylastes cunicidarius (black spruce 

 bark-beetle), which in parts of Scotland causes damage in young 

 plantations similar to that caused by //. ater ; Trypodendron Uiteatimi, 

 breeding in fallen spruce and stumps, and sometimes in Scots pine 

 and larch, which is injurious oi'ly when occurring in large numbers ; 

 Pityogenes chalcographus, which has not previously been observed in 

 Britain, breeding in fallen spruce stems and suppressed trees in Perth- 

 shire (this beetle probably resembling P. hidentatus in biology and 

 control), and Dryocoetes a^itographus. 



Of insects found in standing woods, the large larch saw-fly, Lygaeoue- 

 matus {Nematus) erichsoni, was observed in parts of Scotland. Very 

 severe sporadic outbreaks of this pest have been recorded in the past, 

 and it is desirable that any instance of it should be reported. In young 

 plantations hand-picking of the larvae is very effective. Pme sawflies 

 of two species, Lophyrus pini and L. mfus, were observed in small 

 numbers. 



The pine tortrix moths attack Scots pine trees of five to twelvf> 

 years of age in various districts. Rhyacionia {Tortrix) huoliana (pine- 

 shoot moth) is the most injurious ; its larva destroys both buds and 

 shoots. P. (T.) turionana (pine-bud moth) destroys the leading bud. 

 ■R. (T.) resinelki (resin-gall moth) forms a resinous gall around the shoot, 

 and causes death of the shoot or twigs above the gall by gnawuag into 

 the shoot. It is doubtful whether any practical measures can be 

 devised against these moths, and it is probable that in many cases 



(701) . b2 



