190 



autumn generation remains longer than the others in the pupal stage. 

 The control exercised by animals, birds, and insects, predaceous and 

 parasitic, is very considerable. All these factors attain their maxi- 

 mum importance during the last generation of the year which 

 hibernates on the stocks as pupae. In March 1914, the author 

 examined 1,003 cocoons taken in 5 different localities in the depart- 

 ment of Gironde. The total mortality ranged from 75 to 93 per cent. 

 Fungus diseases killed from 36 to 59 per cent., ichneumons from 

 13 to 36, predators from 1 to 20, and various causes from 3 to 8. Cold 

 does not affect either Clysia or Polychrosis, owing to their method 

 of hibernation, but it kills their insect enemies and the small per- 

 centages shown in the foregoing figures under this head are explained 

 by the severe weather in January 1914. In summer, physical factors 

 are more important ; while in winter, when the mortality is highest, 

 biological factors are more in evidence. 



OsM ASTON (B. B.). Larch Killed by a Longlcorn Beetle.— ^^Wy. J I. 

 Forestry, London, viii, no. 4, October 1914, pp. 277-279, 3 figi. 

 [Received 16th March 1915.] 



Damage in larch woods by Tetropitim gabrieli var. crawshayi has 

 been observed in localities in North Staffordshire, Berkshire, and 

 Sussex. Eggs are laid in June in crevices in the bark of sickly larch 

 trees of about 6 inches diameter or more. The larvae hatch out in 

 about a fortnight, feed through July and August, and devour the soft 

 bast and cambium layers, penetrating 2 inches or so into the wood 

 prior to pupation ; the larva passes the winter in the pupal cell, 

 usually excavated in the wood, until early April, when it pupates, and 

 the perfect beetle emerges in May. Healthy trees do not appear to 

 be attacked by this insect, but those which for any reason are in a 

 sickly condition are quickly killed ; some damage may be done to 

 the outer layers of the wood, but chiefly the sapwood is damaged. 

 In England, where, as a rule, larch woods contain numbers of trees 

 weakened by attacks of canker [Dasyscypha calycina, Fuckl.] and 

 by larch aphis [Chermes laricis, Hartig], this beetle enjoys very 

 favourable conditions, and it would not be surprising if it should 

 become a pest of some importance. 



Larch plantations should, so far as possible, be cleared of all un- 

 healthy trees. As soon as a tree is attacked, as indicated in summer 

 by wilting foliage, and confirmed by finding larvae at work under the 

 bark, the tree should be at once felled and converted or barked, the 

 slabs or bark being burnt. If there are any green woodpeckers in 

 the neighbourhood, the attacked trees will frequently be first 

 recognised by the pitted bark, and it is evident that, by devouring 

 the grubs, this bird is of the greatest service in controlling the beetle. 

 For new larch plantations, it is recommended that planting should 

 be restricted to localities where the larch is known to thrive ; that 

 pure plantations of larch, which introduce unnatural conditions, and' 

 over-crowding in the pole stage, be avoided. 



