Plant Sanitation. 



122 



[August, 1910. 



two days later, I received what appears 

 to be the same insect infesting the roots 

 of Tephrosia Candida, from the Badulla 

 district. The mature beetle has not yet 

 been discovered. This particular pest 

 has evidently a preference for legum- 

 inous plants, and may give trouble where 

 such plant? are grown for manurial pur- 

 poses. The larva is an elongated white 

 grub, with the parts immediately be- 

 hind the head much swollen. It occupies 

 a tunnel in the lower part of the stem 

 and the root stock, Infested plants 

 should be pulled up and burnt. 



Pests of Erythroxylon Coca. 

 In the last number of this Journal I 

 recorded the occurrence of a leaf-rolling 

 caterpillar upon the Coca plant. This 

 proves to be the larva of a Pyralid moth 

 named Rhodophaia heringi. The insect 

 was reported to be responsible for the 

 death of a number of the plants ; but 

 from specimens since received, it appears 

 that much of the mortality must be 

 attributed to a fungus (identified by 

 the Mycologist as Brown Root Disease. 

 I have also found the omnivorous 'Red 

 Borer' (Ze"uzera coffece) attacking Ery- 

 throxylon, 



Breedimg Places for Mosquitoes, 

 It is often difficult to trace the source 

 of a sudden outbreak of mosquitoes on 

 the premises. There may be nothing 

 but running water in the vicinity. 

 Care may have been exercised in the 

 removal of any discarded vessels that 

 could collect water and harbour mos- 

 quitoe larvae. And yet mosquitoes may 

 be troublesome. 



I have recently examined a quite 

 unsuspected source of infection. There 

 is a cacao field close to my bungalow. 

 When the fruit is periodically collected 

 it is broken open at the side of the road, 

 and the seeds removed to the factory. 

 The empty cacao husks are usually 

 buried. But, sometimes, when labour 

 is required for other works, the husks 

 are thrown into a shallow pit and left 

 uncovered. An examiuation of one such 

 heap showed that rainwater had collect- 

 ed in the shells, each of which contained 

 about half a teacupful of putrid liquid. 

 I call it liquid, but the contents were 

 almost a solid mass of mosquito larvae and 

 pupae. The inhabitants of a single shell- 

 gathered at random — were sorted out. 

 Without taking into consideration the 

 very minute newly-hatched insects, 250 

 larvae and pnpae were counted. They 

 were all of one species — Desvoidea 

 obturbans. This is the larger banded 

 mosquito that frequents the verandahs 

 of bungalows and inflicts a very painful 

 bite. As there were at least fifty pods 

 jn the same condition, it is evident that 



a very troublesome outbreak of mosqui- 

 toes may emanate from such a source. 



The fields on each side of many of the 

 small railway stations are usually 

 strewn with empty ' kurumba' husks. I 

 have never had an opportunity of ex- 

 amining them, but it is probable that 

 these may be an even more fertile source 

 of infection, as they can hold so much 

 more water. 



Prevention of Flies. 



The following note appeared in the 

 Madras Mail of July 15th :— 



"Captain E. Owen Thurston, I.M.S., 

 has written to the Indian Medical Gazette 

 a short account of his experience of 

 treating flies with formaldehyde. The 

 method he used was to leave standing 

 basins containing a two per cent, solu- 

 tion of formaldehyde, and he found that 

 the number of flies in the Gaya Pilgrim 

 Hospital at which he was working wa? 

 very much reduced. The addition of 

 two per cent, of formalin to water is not 

 poisonous to man or dog ; but it quickly 

 proves fatal to a fly that has not 

 strength of mind to keep away from the 

 flower vase or other vessel in which the 

 liquid may be placed." 



MISCELLANEA: CHIEFLY 

 PATHOLOGICAL. 



By T. Petch, b.a., b. sc. 



A correspondent recently wrote that 

 he had been advised (from home) that in 

 order to secure a good renewal of bark 

 in Hevea it was necessary to let the sun 

 have access to the stems ; and he wished 

 to obtain further information on the 

 point. There have been no experiments 

 bearing directly on this subject, and 

 even the process of baik renewal after 

 tapping has not yet been investigated ; 

 but from ordinary botanical theory the 

 answer is, briefly, that it is not neces- 

 sary ; indeed, from the point of view of 

 bark renewal only, the advice is just the 

 opposite of what should be given. But 

 as usual there are several factors to be 

 considered before a workiug conclusion 

 can be arrived at. These factors do not 

 seem to be clearly recognised, as is 

 evident from the statement that the 

 bark will renew satisfactorily in two or 

 three years on widely planted trees, but 

 will require four years on closely planted 

 trees. So it may be expected, ulti- 

 mately. But in the meantime owners 

 of closely planted trees will probably 

 have an opportunity of again declaring 

 that botanical theory is incorrect. 



There is a well-known experiment 

 which is now included in most element- 



