THE TROPICAL AGRICULTURIST. 
713 
The " Mango Pijral " (^Orthaza euadrusalis, Walker). — It is a by no means uncommon thing to 
find the foliage on one side of a mango tree completely destroyed, the leaves withered and riddled 
with holes and matted together with web. I have recently ascertained that the insect responsible 
for this damage is the caterpillar of a pyralid moth, Orthaza euadrusalis. 
Helopeltis Antonii, Signoret. — This well-known insect, sometimes called " Mosquito Blight " 
from a fancied resemblance to the common mosquito, has been a source of considerable annoyance to 
both tea and cacao planters. On tea estates in the Kelani Valley and Kalutara Districts the pest 
annually causes an enormous loss of flush. This may possibly be considered a not unmixed evil by 
those who are now advocating a reduction of our outturn of made tea ; hxit as the loss falls very 
unevenly, it can scarcely be considered a beneficial insect. Althovigh the knowledge of the breeding 
habits of the insect enables us to attack it at its most vulnerable stage, much yet remains to be 
discovered of its life-history. The most pressing problem is, What becomes of the insect during the 
months when it deserts the tea plant ? It is only careful observation at a number of different 
stations that can give us any clue to the solution of this mystery. A circular is now being prepared, 
setting forth what is known about Helopeltis and what remains to be discovered. 
The Helopeltis insect attacks the cacao plant in a different manner. Though there is 
occasional injury from the puncturing of the young cacao leaves, the principal damage is confined to 
the pods, which are often so badly punctured when quite young that they are unable to develop 
properly, or may even be killed outright. 1 have suggested the spraying of the young pods, at the 
time when the eggs of the insect are being deposited, with Macdougall's solution or some similar 
insecticide. This treatment is now being carried out on a few estates with apparently good effects. 
Thrips. — A serious attack of Thrips was reported from Kurunegala District in September. 
The species appear to be the same as has been recorded from the tea plant, but in this case it was 
injuring cacao trees. I made a personal visit to the estate in question, and found the damage had 
been really severe. The insect is a most minute one, only just visible to the naked eye. But the 
work of myriads of individuals results in an excessive loss of leaf and endangers the safety of the 
crop. The symptoms of attack are a yellowish blotchy appearance of the upper surface and a 
brownish discolouration on the under surface, which is also covered with small black spots due to the 
deposition of the excreta of the insect. No eggs could be found ; but on crushing the body of the 
female insect and examining it with the microscope a powerful serrate ovipositor is noticeable, 
which suggests a probability of the eggs being embedded in the tissues of the plant. It is probable 
that they are deposited in the younger leaves after these have attained their full size, but before 
they have become hard. On such leaves the adult insects are found, but few, if any, of the 
immature individuals. The actual injury to the leaf occurs after it has reached maturity. It was 
most noticeable that plants growing under dense shade were less affected by the pest than those in 
more exposed situations. It was also apparent that hardy hybrids, when once they have reached 
the fruiting stage, are able to withstand the attack very much "better than do the old red varieties. 
The young hybrid plants do not share this immunity, and often succumb to a bad attack. On this 
account, although it would be quite impracticable to treat a large area with many trees over 20 
feet high, attention may be given to the supplies with great benefit, to enable them to reach the 
immune stage. Such supplies might be sprayed with any of the soapy insecticides in the market. 
It may be necessary to repeat the treatment at intervals during the critical period. 
A case of death from the sting of the common hornet, Vespa cincta, Fabr., has been brought to 
my notice. It appears that a cooly boy, aged about twenty, disturbed a hornet's nest while pruning 
a tea bush. He was badly stung at 3 P.M., and died before midnight. 
A case of bite from the so-called " Tarantula spider," Poecilotlieria suhfusca, occurred in the 
gardens. The man had been struck in the foot and appeared to be suffering considerable pain. I 
could find no definite wound. Six days later he was still laid up and was complaining of pain in 
both arms and legs. His eyes were affected, the surrounding parts swollen. On the day after the 
bite he was unable to see clearly, but this symptom was slowly passing off. There was no local 
suppuration or inflammation. 
Mosquitoes and Malaria. — So much attention has recently been drawn to the connection 
between malaria and mosquitoes, and the question is of such importance, that a few remarks on the 
subject may not be out of place here. Whatever the opinion may be as to whether it is the sole 
cause, I believe that no one who has investigated the evidence fails to acknowledge that the mosquito 
(or rather one particular genus of mosquitoes) is a material cause of infection. If we believe that 
the mosquito plays its part in the dissemination of the disease, we must also recognize the importance 
of offensive and defensive action against the insect that carries the germs that induce malarial fever. 
• Offensive action is practicable only under favourable conditions. In some towns and situations, 
where the nature of the land allows of free drainage, or where there is little surface water, it may be 
