64 PROTECTION OF PLANTS, 1917-18 



just now coming again into prominence, since the scarcity of its parasites has 

 allowed it to breed to such great numbers. Eventually they will again effect its 

 control, in time probably to save the life of the trees, but not soon enough to 

 prevent much injury in addition to the disfiguration of the trees during the 

 summer. 



A few of our native birds feed upon hairy caterpillars such as the white- 

 markedg tussock, and are important factors in natural control in sections where 

 they are still numerous. Unfortunately, man and the English sparrow have 

 united to drive these useful birds away from the neighbourhood of our cities, 

 towns, and larger villages, with the result that the white-marked tussock and 

 other destructive insects find our centres of population more acceptable to them 

 than the open country. The protection and encouragement of our insectivorous 

 birds is a most important method of insect control. 



Control Methods. 



One of the most important methods of preventing serious insect injuries is 

 found in the provision of the best possible conditions for tree development. 

 Proper surgical treatment to remove rot infections and fill the resulting cavities, 

 and to support the weakened parts with cement, iron bolts and chains, so as to 

 prevent breakage, as well as the provision of abundant water in dry seasons, and 

 general precautions against injurious insects, help the trees to a vigorous condition 

 that withstands more successfully the severe periodical insect outbreaks. 



The life-history of the white-marked tussock discloses tw'O periods, the egg 

 and the lar\^al stages, during which control measures may be successfully applied. 

 The eggs may be destroyed, and the caterpillars may be killed by poison. 



The Destruction of Egg-Masses. 



The more effective and economical method for application in cities and towns 

 is usually considered to be the destruction of egg-masses during the dormant 

 season, combined with banding the tree trunks. Fortunately the white masses 

 are so conspicuous that they are at least easily observed. The species is present 

 in the egg-stage for practically ten months of the year, in this climate, and a long 

 period is thus offered for the removal of the egg-masses. 



If the eggs are entirely removed from a group of trees during the fall, winter, 

 and spring, and the trunks are properly banded to prevent reinfestation by wander- 

 ing caterpillars, the foliage will be completely protected from tussock caterpillars 

 for the season. 



