196 



THE PROTECTION OF WOODLANDS. 



Fig. 38. 



\ 



Elm-bark Beetle, magnified 

 five times. 



bores through the bark in June, forming a vertical tunnel 3 or 4 in. 

 long in which eggs are laid. Larvse hatch out in autumn and feed on the 

 inner bark (forming secondary -galleries) till the following spring or early 

 summer, when they pupate and emerge 

 through the bark as adults either in August 

 or the following spring. After pairing, the 

 2 again bores into the bark and lays her 

 eggs, and so on till the stem is girdled, and 

 the tree becomes diseased or killed. Trees 

 from which beetles have emerged look as if 

 riddled with shot ; and fine sawdust will be 

 found on the bark or at the foot of the tree. 

 They generally attack healthy and vigorous 

 stems, as well as unhealthy trees. In Britain 

 usually only a few beetles emerge in August. 

 Extermination. Moribund trees attacked are 

 best felled and barked late in July or early in 

 August, and the bark burned. The rough 

 outer bark of trees showing bore-holes can 



be spoke-shaved to kill the larvae by exposure, and by the flow of sap ; and 

 insecticide washes can then also be applied. 



*The large Pine-shoot beetle, Hylesinus piniperda (Fig. 39-41), is very 

 destructive in Pine-woods, attacking plantations of nearly all ages. Far 

 less damage is done by the larvae than by the beetle. Owing to strong resin- 

 flow from healthy stems, it chiefly attacks felled timber or sickly planta- 

 tions, healthy trees being only attacked after excessive increase. Attacks 

 are usually worst along green lanes and in pole-woods near timber-depots 

 or saw-mills. The beetle is ^ to in. long, almost cylindrical, at first 

 reddish-brown, then glossy black or dark-brown, thorax black, feelers and 

 legs reddish-brown. The shield-wings have longitudinal rows of fine 

 punctures, with the spaces between wrinkled with punctures and small 

 knobs, and having a row of little knobs with brush-like tufts of thick hair. 

 Beetles emerge from their pupal-chamber or their winter quarters late in 

 March (in dry warm years) or in April, pair and lay eggs in newly-felled 

 stems or stacked fuel, sickly trees, or fresh stumps of Pine, Spruce, and 

 Larch. After pairing, the $ bores under some bark -fissure, and lays eggs 

 along a vertical main-gallery about 4 in. long. Boring and egg-laying 

 continue for 3 to 5 weeks, up to 100-120 eggs being laid closely in niches 

 to right and left along the edges of the main-gallery, the bore-hole being 

 sometimes marked by resin-outflow. In 2 to 3 weeks the larva) hatch 

 out and eat sinuous galleries on each side of 'the main-gallery, and about 

 8 weeks later pupate for about 14 days in pupal-chambers formed in the 

 bark ; and the beetle usually issues in June, about 11 to 12 weeks after the 





