328 



PROTECTION AGAINST INSECTS. 



c. Relations to the Forest. 



The caterpillar attacks the common Scots pine, rarely 

 other pines, the spruce or silver fir, and prefers 20- to 40- year- 

 old trees, but will even attack trees up to 60 years of age. 



The needles are eaten from the beginning of July to the 

 end of October, but not the buds. At first the shoots of the 

 current year are spared, but later on they are also attacked. 

 The young caterpillars gnaw the sides of the needles (Fig. 166) ; 

 as they get larger they eat down to and beyond the mid rib. 

 The full - grown larvae cut off the 

 points of the needles, but eat the 

 remainder completely. Complete 

 defoliation seldom results in the 

 death of the trees, as the attack 

 commences late in the season, and 

 the buds well provided with reserve 

 material produce fresh foliage the 

 ensuing year. Only when a wood 

 has been seriously attacked for two 

 successive years, the second attack 

 destroying most of the needles, do 

 the trees die. If, however, a cold 

 and prolonged winter should succeed 

 a somewhat early attack of the pre- 

 ceding year, the buds may become 

 too weakened to produce useful 

 needles and the trees may die, after 

 one attack only. As long as the cam- 

 bium is found healthy the wood may be saved. It is there- 

 fore unnecessary to commence immediate felling of defoliated 

 woods, as after an attack of the pine-moth. Dense woods in 

 sunny aspects of warm hill districts are preferred by this 

 moth, and windy borders of the woods are avoided. 



Fig. 167. Scots pine needles 

 attacked by G. piniaria, L. 



d. Protective and Remedial Rules. 



Mix beech with conifers. 



Protection of enemies, as for Trachea pinipcrda. 



Admission of pigs from October to April (50 pigs to 500 acres). 



