714 
THE TROPICAL AGRICULTURIST. 
quite possible to exterminate the malarial mosquito by depriving it of its only breeding grounds. 
But such conditions are seldom found in Ceylon. 
Defensive action, on the other hand, is always possible. The malarial mosquito {Anopheles 
species) flies only after sandown. It seldom flies high above the ground. Mosquito netting and 
upstair bungalows will be the logical policy to meet these two cases. There is of course a period, 
between sundown and bedtime, when — unless we have made our houses mosqiiito proof — we are 
unprotected by mosquito netting. Daring the evening the feet and ankles are particularly liable to 
attack. To guard against this it may be suggested that boots might be worn in the evening instead 
of shoes. The after-dinner nap is another dangerous time, when the mosquito can take his fill withotit 
interference. It would be easy to fit up a small mosquito-proof retre:it in the verandah of most 
bungalows, large enough to contain a small table and a couple of chairs, where it would be possible 
to read (or sleep) in safety and comfort. Those who (like myself) have satisfied themselves of the 
accuracy of the facts recorded by recent distiugnished investigators, that the Anopheles is the sole 
carrier of infection, and that the malaria parasite cannot exist outside the body of either the man or 
the mosquito, recognize the importance of isolating and medically treating every single case of 
malarial fever, and of so preventing the mosquito from acquiring fresh infection, for, unless the 
Anopheles has previously drawn a supply of the malarial parasite from some fever-stricken patient, 
its bite is quite harmless. Natives who have to sleep in malariotts localities may protect themselves 
by covering the exposed parts of the body with oil. 
In connection with the Mosquito-malaria Theory, the British Museum authorities have called 
for specimens of all the different species of mosquitoes to be found in various parts of the world. I 
have sent to England, for determination, some fifteen distinct species, and I understand that other 
collections have been made and forwarded by members of the Medical Service. 
Besides the danger of malarial infection from the bites of Anopheles, the discomfort and irri- 
tation caused by the bites of the ordinary species of Culex are not to be disregarded. These species 
can find convenient breeding places in any chance accumulations of water about a bungalow. Tubs 
of water should not be allowed to stand undisturbed, or will soon become filled with the small 
wriggling larvae of the mosquitoes. Water standing in the saucers of flower pots, in any discarded 
cans or tins or broken bottles, will also serve to increase the number of insects. All such receptacles 
should be repeatedly emptied. Another prolific source of mosquitoes is to be found in the hollows 
of the bamboo stumps after the stems have been cut down. I have recently made a careful exami- 
nation of the giant bamboo clumps in the Botanic Gardens, and have estimated the number of 
mosquito larvae existing in the stumps at any one time. The result of my calculations worked out 
at the enormous figure of 57,000 larvae within the area of the Peradeniya Gardens. The larval and 
pupal stages of the insect occupy from ten to fifteen days according to temperature. Allowing for 
two generations only per month, for the eight months during which water is likely to remain in the 
bamboo stumps, we must multiply the above figure by sixteen, producing the total of 912,000 (close 
on one million) mosquitoes raised from these bamboo clumps in one year. To the above must be 
added the number breeding in the stumps of the common yellow bamboo, which remains to be esti- 
mated. This vast swarm of mosquitoes may (and in future will) be prevented by the simple 
expedient of trimming off the bamboo stumps to the next knot and leaving no receptacle for the 
accumulation of water. 
Beneficial Insects.— 1 regret to have to report the final loss of the small colony of imported 
ladybirds that has been cultivated for the last three years. These beetles were received from the 
Cape, where the species {Exocliomus nigromaculatus) is said to be most useful in checking some of 
the local scale insects. But it is apparently unsuited to our work in Ceylon. It does not breed 
sufficiently rapidly, and in fact ceased to breed at all after the first eighteen or twenty months. The 
adult beetles remained alive for a surprising length of time, but died ofi: one by one until the colony 
became extinct. The several lots of beetles liberated from time to time have shown no signs of having 
established themselves, and have presumably acted in the same way as those kept in captivity. This 
failure does not necessarily mean that the introduction of beneficial insects to fight existing insect 
enemies is useless. It only means that we have not yet introduced the right kind of insect for our 
purpose. 
1 have been experimenting on the introduction of the cochineal insect {Coccus cacti) and the lac 
insect ( Tachardia lacca). Through the kindness of Mr. Loimsbury, Government Entomologist at 
Cape Town, I have received living colonies of the cochineal insect, and have found no difficulty in 
establishing them on plants of both Opuntia Coccinellifera and 0. Dillenii. Similar attempts to 
procure living colonies of the lac insect from India have so far failed. Through the courtesy of Dr. 
George Watt, I have received repeated consigaments of the insects from various districts, but in each 
case the younji larvse have died in transit. 
