COMMON COCKCHAFER. 



203 



of a swarm-year also eat all wire-worms and other larvae they 

 meet with, besides the plants. 



These swarm-years have been little noticed in Great Britain 

 and appear to be less marked than on 

 the Continent, the number of chafers a i 



appearing each year being more uniform. 

 There was a swarm-year at Egham, in 

 the Bagshot sand district, in 1898. 



The flight of the cockchafer is some- 

 what heavy, it flaps its wings up and 

 down many times before ascending from 

 the ground, in order to drive air into its 

 trachae. It can endure unfavourable 

 weather tolerably well, and the larvae can 

 withstand a month's inundation 3 feet deep. 



c. Relations to the Forest. 



The cockchafer is injurious, both in the 

 laval and perfect condition. The attacks 

 of the larvae are less visible, but are more 

 harmful, especially in coniferous woods, 

 as they affect the roots and last for two 

 or three summers. They are worst in the 

 two last summers. Scots pine and spruce 

 up to 10 years old are most endangered, 

 then the larch, and the silver-fir does not 

 escape. Broadleaved trees do not suffer 

 from the larvae quite so much as conifers, 

 but nearly every species is attacked, those 

 with tender roots, such as beech and ash, 

 being preferred to species like the oak, 

 which speedily develops strong roots. The 

 bitten surface is rough and fibrous, and not 

 smooth as when bitten by a pine-weevil, 

 or gnawed by a mouse, the work of which 

 latter can be readily distinguished by the characteristic paired 

 tooth-marks. 



The larva is extremely destructive in forest- and orchard- 

 nurseries and in broadcast sowings ; whole rows of young 



Fig. 76. Scots pine 

 roots attacked by 

 chafer grubs. 

 a Three years old. 

 b Two years old. 



