270 PROTECTION AGAINST INSECTS. 



of their assimilating organs, indirect damage is also done b}'^ 

 reduction of the cover, and consequent exposure of the soil. 

 As the cover of Scots pine woods is apt to open out even 

 under favourable conditions, this form of injury is very serious. 



Exceptionally, the beetles in summer eat out irregular 

 longitudinal galleries in the first 5 to 6 years' growth of shoots 

 on vigorous 12- to 15-year-old Scots pines, but without laying 

 any eggs. Altum* states that these galleries, which run partly 

 in the bast, partly in the sapwood, are only used to harbour 

 the beetles. 



Lastly the beetle does damage by boring down for 2 or more 

 inches to the sapwood of the rootstock of sound standing trees 

 in order to hibernate. If this should happen on a large scale, 

 the trees might die, or at any rate would become sickly and 

 attract more beetles in the ensuing spring. 



The pine-beetle prefers forests in flat or undulating country, 

 isolated trees, trees along the borders of woods, and those 

 which have suffered from tire ; it is also common near timber- 

 depots. Like all bark-beetles, it prefers whidfalls or trees 

 partly uprooted by the wind, and sickly trees, but does not 

 exclusively attack such trees. 



In a pine forest on the peninsula of Darss on the Pomeranian 

 coast, which had been flooded with salt water on the 12th and 

 13th November, 1872, and the trees thus rendered sickly, the 

 beetle appeared in such enormous numbers as to completely 

 destroy 2,500 acres of the forest. 



In the spring of 1892, about 100 acres of pine wood was 

 burned near Caesar's Camp, in Windsor Forest. The next year 

 there was a serious attack of pine-beetles, the trees that had 

 been singed by the fire having multitudes of larvae between 

 their bark and wood. These trees had all to be felled, while 

 the surrounding forest trees were pruned in the most 

 unsiglitly manner by the beetles. 



d. Protpclivc nuJrf!. 



i. Timely and frequent thinnings of pine woods, and quick 

 removal of all sickly trees. 



* " Ein neucr Sommcraufenthalt von M. p'ni'i perdu,'' /rifiirhr.fr. Frxf. v. Jf/ilii\, 

 ]87!t, page 204, 



