THE AUSTRALIAN NATURALIST. Vs 
its development and food plant, is of more practical value than 
a. hundred technical descriptions unaccompanied by any other 
information. 
The advances that have been made-in economic zoology dur- 
ing the last twenty years have done a great deal to popularise 
this branch of science, and to show its commercial value. The- 
study of the relations of insects and disease is only just in its 
infancy. It has been proved that the bites of mosquitos in mal- 
aria-stricken country are the means of spreading tropical fevers ; 
and that in the same way fleas that infest plague-stricken rats 
may, when they bite human beings, infect them with plague. 
The red water disease of cattle, that swept over Queensland 
about ten years ago, and still exists in many districts, was 
carried from infected animals to healthy ones by cattle ticks, 
and it was not until it was found out that while the innocuous. 
ticks that were not virulent with redwater -bacili caused tick 
worry, through the immense numbers that infested the cattle, 
it was the bacilli-germ infested ticks that caused the more: 
serious redwater ; and when the first was treated by dipping, 
and the last by innoculatim, they were kept in hand. The spread 
of disease by insects that feed upon filth or decaying matter— 
particularly the Diptera or two-winged flies—is a well estab- 
lished fact, and the old idea that flies were useful, as they were 
scavangers and ate up decaying matter, is quite at a discount. 
The prompt burning, burying, or liming of all, such matter 
has lessoned diseases in a wonderful manner. Flies are known 
to spread disease germs in two ways—first, by flying into 
and contaminating our food, by which means germs of typhoid,.. 
cholera, etc., are introduced ; or inducing blood poisoning by 
settling on open sores or cuts. Many deaths in the country 
have been thus cansed by an insignificant fly. 
The fauna and flora in the immediate neighbourhood of the: 
city are being rapidly exterminated. Fyery year we find houses 
and gardens taking the places of native scrub. Many fine in- 
sects in the Macleay Museum collections were taken by Mr. 
Masters about Hlizabeth Bay, Petersham, and other places 
quite close to the city; these have now vanished from those parts. 
Hven ten or twelve years ag, all round Rose Bay, Mosman, 
and North Shore one could find large patches of flowering 
Angophora, Leptospermum, and other shrubs. which have been 
cleared off to make room for houses, thus every year forcing 
collectors further afield. With the destruction of plant and 
insect life small mammals and birds die out, or move back 
before civilization. 
I have found that the advent of large numbers of honey bees 
into a district will soon spoil it as a summer collecting 
ground, because when domestic bees swarm over flowers our 
indigenous insects leave in disgust. Introduced weeds and 
