INSECT PESTS 139 



than 25,000 acres of pine woods in the neighbour- 

 hood of Nuremberg were utterly destroyed by the 

 caterpillar of Fidonia piniaria. In Bohemia between 

 1872-76, 175,000,000 cubic feet of spruce was 

 killed by the bark beetle, Tomicus typographies. 

 In 1890-92 no less than 15,000 acres of spruce 

 immediately north of Munich was stripped bare 

 of needles and killed by the nun moth Liparis 

 monacha. A few years later, the very existence 

 of the Saxon woods was threatened. Twenty 

 years earlier at least a thousand acres in Poland 

 and in Russia were devastated. The history of 

 continental forestry is full of records of such 

 incidents. To convince the forester of this country 

 of the dangers of insect attacks one has only to 

 mention the pine weevil Hylobius abietis. This 

 insect if left to itself can undo the most careful 

 work of the forester. In the ideal conditions 

 presented by a new plantation on land which 

 still bears the undecayed stumps of felled trees, 

 the insects appear from somewhere and multiply 

 with amazing rapidity. Their food is the tender 

 bark of the young trees. They eat it down to the 

 cambium layer and the trees may be killed. Land 

 which has been attacked and on which no preven- 

 tive measures have been taken has invariably to 

 be replanted, and in many cases, where the per- 

 sistence is commendable but the lack of knowledge 

 lamentable, replanting has had to be done not 

 only twice but even three and four times. The 



