222 A. G. HAMILTON. 
of drought, (3) Bushfires, (4) Difference of soil, (5) Sheep manure, 
(6) White ants, (7) Caterpillars destroying bark, (8) the blacks’ 
opinion—the ravages of opossums, with which last he coincides 
and adduces strong evidence in favour of that view. The increased 
number of opossums arises from the destruction of their natural 
enemies, the blacks, dingoes, eagle hawks, and lace lizards. 
The seventh theory advanced, viz., caterpillars destroying bark, 
of course fits in well with what was mentioned before. Insects 
indubitably do work great destruction among gum-trees. I have - 
seen a forest of gums near Home Rule dead from, as far as I could 
notice, the effects of their being infected with Coccide. The beetles 
of the genus Anoplognathus at times swarm in trees like bees, 
and completely strip every leaf off, and if this does not kill them, 
it at least renders them unhealthy. In the discussion on Mr. 
Macpherson’s paper, Professor Liversidge thought the decay 
of the trees might proceed from exhaustion of the soil.* 
Another theory advanced was that on the death of an aboriginal, 
certain ceremonies were gone through, including the killing of a 
tree, but this would account for very few, and indeed in many 
parts where forests are dying there have been no blacks for the 
last half century. 
Mr. K. H. Bennett in a paper on the subject is strongly of 
Opinion that gum-trees, especially Hucalyptus rostrata and £. 
melliodora, are killed by opossums, and attributes their great 
increase to the passing away of the blacks. + 
During the past few years the southern parts of the Colony of 
New South Wales has been visited by immense hordes of grass- 
hoppers and also Hemipterous insects. The former destroyed all 
kinds of crops and trees, and the latter were very destructive to 
the vines. Now such a visitation is without doubt due to some 
disturbance of the balance of nature, whereby these insects were 
not so much preyed on by their natural enemies. 
* Journ. of Roy. Soc. of N.S. Wales, 1885, p. 83. 
+ Proc. of Linn. Soc. of N.S. Wales, Vol. x., p. 453. 
Pose + 
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