148 Control of Parasites 



fed, the main remedy is not to allow trees to get into such 

 vulnerable condition. If a slight infection is noticed in 

 time, in addition to promoting the general vigor of the 

 tree, an application of whitewash witli Paris Green added, 

 or of strong whale-oil soap suds with a little crude carbolic 

 acid added, repeated as needful, may be employed. It may 

 also be possible to cut out small infested areas of wood, and 

 treat them antiseptically like other wounds. This has been 

 successfully done on old elms at Brussels. 



In the forestry practice of Europe, baiting of bark-beetles, 

 which are specially destructive to spruce forests, is the only 

 practical remedy besides clean lumbering. The beetles 

 thrive most readily under the bark of the freshly felled timber, 

 and, therefore, barking the trees immediately after felling, 

 and the removal or burning of rubbish is practised. In 

 addition, in the spring, a few "trap trees" are felled or 

 billets laid out in the endangered places, on which the beetles 

 assemble in large numbers to lay their eggs; the trap trees 

 can then be removed and burned. 



If the pest is once established, nothing can be done, except 

 to cut out the infested trees in order to avoid further spread. 



Root Destroyers. The root pests — such as the cut-worms, 

 larvae of certain moths; the wire-worms, larvae of the well- 

 known chcking-beetles; root-lice, like the celebrated Phyl- 

 loxera, which made such ha\'oc among the vineyards of 

 France, and other plant-lice, which feed on roots either 

 wholly or at some time in their development — these are 

 more to be feared for the lawn grass and other tender plants 

 and for young tree seedhngs, than for older trees, although 

 they occasionally injure these too. Those which spend 

 one phase in the open (and then they are also sometimes 

 feeding on foliage, as the clicking-beetles and lice) may be 

 decimated by poison or by collecting during that phase. 



