119 
ERRORS OF THE TREE PLANTER. 
sea it also requires protection against saline winds. There are many valuable 
stands of this species in Canterbury; but as one travels through the district great 
difference is noted in the. aspect and vigour of the trees. The difference is 
pumaiily due to diversity in the sub-strata over which the trees have been planted. 
On diy parts of the plains the foliage is liable to be eaten away by insects faster 
than the vital resources available can replace it. On good aluminous land with 
adequate rainfall or abundant soil moisture, the trees suffer less loss of foliage and 
can easily replace by new growth that which has been lost. Insect allies will help 
the debilitated trees even when they are unsuitably located on dry land; but the 
wise forester will in future plant his E. viminalis only where the conditions will 
ensure for it persistent and strongly resistant vitality. * 
A third example will be fittingly supplied by the greatly valued E. rostrata. 
This species grows naturally in all the Australian States except Tasmania. Its 
habitat is usually on low country in the vicinity of streams and rivers; and where 
it spreads on to dry uplands it declines in vigour and becomes liable to severe 
injury by insects. A belt of low-lying and sometimes flooded land along the River 
Murray in New South Wales and Victoria provides the conditions for its optimum 
or best development. Its dense red heartwood has a reputation for durability in 
the ground equal to that of our own best totara. Planters in New Zealand early 
included it amongst their selected species. Unfortunately while they looked 
forward in the hope of reaping crops of this precious timber they did not know 
or did not remember that the species could be successfully cultivated only on good 
alluvial land where the winters were mild. Of the many thousands of plants that 
were propagated and distributed, only a few were so fortunate as to be favoured 
with quite congenial conditions. Some were planted over dry shingle beds; some 
too high above sea level; some too far south. The foliage of this species is very 
palatable to the leaf-eating weevil, and the trees have been generally attacked by 
this insect. Specimens fortunately placed have been able to resist or endure the 
enemy and maintain their vigour while those planted where nature had pre¬ 
determined that they should not flourish have been depressed and dwarfed. 
The conclusion to which this research leads is obvious. The several species 
of Eucalyptus under cultivation in New Zealand differ greatly in their 
palatableness to insect enemies. Some are attacked only very slightly; others more 
severely; a few seriously. Resistance to the attacks depends first and mainly 
upon healthy sap and abounding vitality in the trees, and vitality depends upon 
congenial conditions of climate and soil. But here as in Australia the counter 
attacks of friendly insects are necessary to maintain the balance of vital forces. 
Each species must first be given its appropriate location; and then, when the 
planter has done his best the entomologist must stand by to bring in and 
distribute those friendly insects that are known to prey upon the enemies of our 
trees. The owner of plantations must have courage, so that, when he finds any of 
his trees wrongly chosen and unadapted to his locality, he may resolutely cut them 
out and plant others. 
Students who wish to take up research on the forest insects of Australia and 
New Zealand should obtain the writings of Walter W. Froggatt, F.L.S., late 
Government Entomologist, New South Wales, the Bulletin by David Miller, 
B.Sc., F.E.S., issued under the authority of our own Forest Service in 1925, and 
The Insects of Australia and New Zealand by Dr. R. J. Tillyard, M.A., ScD., 
Director of the Cawthron Institute, Nelson. 
