117 
CONDITIONS OF RESISTANCE. 
suffer leas t and those with less resistant vitality that suffer most. J. H. Maiden in 
his I orest T lor a has given much information about the enemies of the eucalypts 
as observed and recorded by scientific men in Australia. 
As immigrants into New Zealand the eucalypts are subject to a warfare 
against insect enemies similar to that which they have successfully maintained in 
their native Australia. Here as yonder there are leaf eaters and sap 
suckers. Here as yonder there is need for healthy sap and strongly resistant 
vitality. Here as yonder there is a place and a function for insect allies, 
lhe readei will better understand our position in New Zealand in respect to insect 
enemies and friends if I quote here a statement kindly contributed by Mr. David 
Miller, B.Sc., Entomologist at the Biological Laboratory, Wellington. The 
statement is as follows: — 
“LIST OF INSECTS INFECTING GROWING 
EUCALYPTUS SPP. IN N.Z. 
The Gum tree Scale (Eriococcus coriaceus Maskell). 
The Eucalyptus Mussel Scale (Lepidosaphes eucalypti Froggatt). 
The Bronze Beetle ( Eucolaspis brunneus Fabricius). 
The Eucalyptus leaf weevil ( Gonipterus scutellatus Bois-Duval), 
The Eucalyptus Tortoise Beetle ( Paropsis dilatata Erhorn). 
The Green Chafer (Pyronota festiva Fabricius). 
The Elusive Tortrix ( Tortrioc ecccessanaWa\ker). 
The Blue-gum Leaf-tyer (Eucosma plebeiana Zeller). 
The Eucalyptus leaf-roller ( Spilonota macropet ana Meyrick). 
The Blue gum Gall chalcid ( Rhicnopeltetta eucalypti Gahan). 
The Eucalyptus Psyllid (Rhinocola eucalypti Masked). 
With the exception of the Bronze beetle, the Elusive tortrix, and the Green 
chafer, which are native to New Zealand, ad the above named insects are 
importations from Australia. Only three species can be considered as major 
pests; these are the gum-tree scale, the leaf weevil, and the gad chalcid, the scale 
and the chalcid being most destructive. The scale does not confine its attention to 
any one species of Eucalyptus though its attacks are most severe upon E. globulus, 
while such species as regnans, obliqua and viminalis, for example, are better able 
to withstand infestation. The scale is controlled by the ladybird (Rhizobius 
ventralis) which has been distributed in the infested areas. This beetle, however, 
is often unable to cope with the pest quickly enough to prevent a considerable 
amount of damage being done. The gad chalcid is confined solely to E. globulus, 
and there is no means for control available at present.” 
It should encourage planters to know that the worst of the insect enemies 
in this rather long list are importations from Australia where the eucalypts have 
survived and dourished for thousands of years. Enemies that have failed to kill 
these trees in their native home may surely be assumed to be incapable of killing 
them in any other country where the trees can be given equal advantages of soil and 
climate. But what nature has accomplished in Australia in establishing and main¬ 
taining a balance of vital activities we must achieve in New Zealand by our own 
