JuNSi 2, 1902.] Siqiplement to the " Tropical AgricuUmist!" 
859 
requisite would be to keep tlie weeds within 
reasonable bounds. 
I have seen youug trees parched and struggling 
on a dry soil during the hot weather, while 
others of the same age were green and flour- 
ishing amid lantana scrub. This was in the 
Chilaw district. 
I have also seen full-grown trees looking 
decidedly cool and comfortable with a dense 
Hndergrowth of leguminous weeds in the 
Kurunogala district. 
I should like to have the views of experienced 
planters on these points:— (1) Whether they 
approve of keeping young coconut palms for 
a few years amid low jungles but protected 
from over-crowding by creepers, &c., in order 
to provide shade and conserve the soil mois- 
ture, or whether they would recommend plant- 
ing leguminous shade trees (Erythrinn) to be 
gradually removed later on. (2) Whether they 
approve of keeping an undergrowth of weeds 
(preferably leguminous) in old plantations. 
If not, what objections they have in the carry- 
ing out of these suggestions. 
Yours truly, 
C. P. 
[Here are a few interesting points for some 
of our subscribers (and among them are many 
experienced coconut planters) to attack during 
a leisure hour. 
Clean cultivation our correspondent is no doubt 
ready to admit is a sina qua non under certain 
circumstances, but he evidently desires to have 
the views of experienced hands on the depar- 
ture he proposes in the special case of coco- 
nuts and other large trees. A gentleman who 
possesses a large plantation of mangosteens 
whispered it to us as a secret that it is kindness 
(in the shape of too much attention) that kills 
the young mnngosteeu : and he showed us some 
hardy plants which looked double their age, 
flourishing as he said " in the jungle." Those 
thinking over the question of growing under 
shade will be interested in the first article in 
the May Tropical Agriculturist, where an account 
of the successful cultivation of pine-apples under 
shade is given.— Ed. A.M.] 
THE ENTOMOLOGY OP THE HOUSE PLY. 
(Continued.) 
Many of the habits of the fly are painfully fami" 
liar to all of us. Its discordant buzzing, its exaa' 
perating persistency in returning again and again 
to our sensitive bald spots, setting our nerves on 
edge with the tickling of its feet and the rasping 
of its proboscis and its headlong floundering into 
the milk jug and coffee cup ; likewise its habit, so 
distressing to. the careful housewife, of marking 
its path, especially on newly-polished mirrors, 
with little dots of brown-black excrement, are well 
known to almost everybody. If the fly was a cleanly 
insect, the importance of these associations with 
man and man's belongings would be limited by the 
temporary annoyance caused. But the house fly 
is far from cleanly. It breeds in dung' and returns 
to dung to lay its eggs, it flits direct from sup 
purating sores on the skin of animals to regale 
itself on our perspiration ; it visits stercus, and 
then, perhaps, the milk pail. 
Numerous diseases, some of tliem most serious 
in clinracter, may result from tlie visits of the fly 
to our food and our parsons, for it oft brings with 
it virulent germs from the faecal or putrid mutter 
which it has visited. It has been demonstrated 
that the fly can contract plague from feeding on 
animals that have died of this disease, and that, 
having contracted plague, it may live for several 
days and finally fall or drop dead on to food, 
meanwhile having been depositing excrement 
laden with virulent bacilli. It is firmly believed 
by mediciil men in India that cholera is very 
frequently transmitted by the house fly. Tuber- 
culosis bacilli are taken up by it through feeding, 
as it often deos, on the sputum of consumptive 
persons, and these germs are given off in the excreta 
The excreta of flies that had been fed on infective 
sputum, when injected into rabbits, has given rise 
to tuberculosis. But of all diseases that it may 
transmit, typhoid or enteric fever probably ranks 
first in importance. The dejections of persons in- 
fected with this disease, it has been stated on the 
best of authority, harbour the causal organism not 
only during the period of actual illness, but for 
some days before and for some time after appar- 
ently complete recovery. The fly becomoi con- 
taminated by alighting on dejections that h(.ve not 
been properly disinfected, and then may carry the 
germs into surrounding households. The bacilli 
multiply rapidly in milk, and how easily can a fly 
render a whole pailful poisonous by falling into it 
or even simply sipping it ! In cities and towns 
with good sewerage systems and well-enforced 
sanitary regulations, the carriage of typhoid by 
the fly is doubtless exceptional, but in concen- 
tration and army cam^s it is presumed to be very 
common. 
Not only may the fly convey infectious diseases, 
but, it is asserted, some of the worm parasites 
that afflict humanity as well. The eggs of the tape 
worm and of the tiny thread or pin worm were 
found to pa.ss unaltered through "flies" (presum- 
ably house flies) by an Italian investigator; and an 
American zoologist found that fly maggots (of 
genus Miisca, species not stated) will devour the 
common round worm, and that the eggs of the 
worm are passed off alive in the excreta of the 
winged adults. The excreta may be dropped on 
the food and the contained eggs carried into the 
intestines, where they can develope. It is 
probable that the life circle of the worm normally 
depends npon such an extraordinary sequence of 
happenings for its completion, but as the eggs 
are almost numberless the survival of the species 
can safely rest on very slim chances of one egg, or 
indeed of any one egg if a thousand besoming 
lodged in the intestine. 
The fly evil can be abated to some extent by 
preventives against multiplication. The thorough 
cleansing of stable floors even once a week, and 
the keeping of manure in pits from which flies 
cannot escape or spreading it on the land where it 
will dry out quickly are practical measures of high 
