244 PROTECTION AGAINST INSECTS. 



but this work need not be carried out till May, in order that 

 the larvae, which may have developed in the logs may be 

 destroyed. Barking in May is also cheaper than in winter, 

 as the work is easier and the days longer. All large fuel logs 

 should be split so that their bark may be limited to narrow 

 strips. They should be stacked with the bark downwards. 

 Stools remaining in the ground should also be barked. 



viii. Trap-trees should be prepared for felling (see e, i.). 



ix. All enemies of bark-beetles should be preserved. Tom- 

 tits, golden-crested wrens and woodpeckers are most important 

 in this respect. When a swarm of bark-beetles is approaching 

 extinction, ichneumon-wasps appear in great numbers. 



e. Remedial Measures. 



i. Trap-trees should be felled from March till September, 

 and should be barked and the bark burned as soon as the 

 larvae are full-grown. Old or somewhat dominated spruce- 

 trees with small crowns should be chosen, especially when the 

 root-stock has been somewhat loosened from the soil by the 

 wind, as such trees are more readily attacked by the beetles. 

 In the spring, whilst the weather is still damp, it is sufficient 

 to fell new trap-trees at intervals of from 5 to 6 weeks, but in 

 summer this should be done at least once a month. The local 

 flight-periods should be followed in this respect, and from 8 to 

 14 days before trap-trees are barked fresh ones should be felled. 



In order to facilitate control the trap-trees should be 

 numbered, and a register kept up to record the development of 

 the beetles. Cogho reckons 5 trap- trees for 100 paces along 

 the boundaries of the felling areas. 



Eatzeburg recommends that the trap-trees should not be 

 deprived of their branches, and that they should be placed on 

 stumps or stones, so that the beetles may bore in from below 

 as well as from above. Most authors agree with this advice, 

 but Fischbach recommends the lopping off of the branches, as 

 then the trees dry up the sooner, and he also maintains that 

 the bark-beetles only attack lopped trees, which is contrary to 

 experience. Hess recommends that the branches be left, both 

 on account of the cost of lopping, and because numbers of 

 bark-beetles of other species are attracted to them. The 



