February, 1909.] 



163 



PLANT; SANITATION. 



THE TEA INDUSTRY. 



THE MOSQUITO BLIGHT. 



By C. B. Antram, 

 Entomologist to the Indian Tea 

 A ssociation. 

 From past observations and our ex- 

 periences of the year 1907, with regard 

 to Mosquito blight, it would seem that 

 everything depends upon the climatic 

 conditions prevailing during the first six 

 or seven months of the year, whether 

 the pest becomes serious or otherwise 

 from about July onward to the end of 

 the season. Without doubt the blight 

 has this year been as serious as in any 

 year since its first discovery, and in July 

 reports began to come in from nearly 

 every part of the tea districts that 

 "Mosquito" was damaging the bushes to 

 such a degree, that certain gardens were 

 practically closed for the remander of 

 the season. This was'the case, not only 

 in one corner of a district, but in several 

 widely separated portions of the whole 

 tea area, the blight generally being, on 

 most gardens, worse than in previous 

 years. In one or two instances only 

 (where the insect had in past years given 

 trouble) were the reports favourable in 

 that there had been no appreciable loss 

 in crop. The following extracts from 

 letters received from planters giving 

 their opinions as to the reason for the 

 current year's excessive attack of Mos- 

 quito blight are interesting and point 

 to the one idea that "Blight" is con- 

 trolled in a very great measure by 

 climatic influences. 



One Cause of Mosquito Blight. 



One Manager writes from Assam, 

 under date the 24th September, 1907 :— 



" I am of opinion that the cause of 

 Mosquito blight appearing so early and 

 in such a severe form this season is 

 entirely due to weather conditions. The 

 cold damp weather which prevailed 

 during the months of May, June, and 

 July, seems to have been especially 

 favourable to the successful develop- 

 ment of the pest, and were it not for the 

 fotunate occurrence of a spell of sun- 

 shine and heat in August which checked 

 its progress, the loss of crop would have 

 been considerable. As ic is, I only 

 estimate a loss of about 200 to 300 

 maunds, while in the last five years the 

 loss has been nominal. Bar a few 



isolated patches, at the end of each 

 season, the pest has done little or no 

 harm here for the last seven years, I 

 may mention that the temperature for 

 the last five years has not been so low 

 in May, June and July, as it has been 

 this year. My experience is that absence 

 of sunshine is invariably favourable to 

 the development of the pest." 



Another planter writes :— This year 

 is one of the worst in this district (Dar- 

 rang) for Mosquito blight since 1902, the 

 weather being so cool and dull for the 

 last three months until the 11th August 

 when we had a change," etc.. etc. 



It is quite certain that the attack of 

 Mosquito as it appeared this year in the 

 Dam-Dim district of the Duars could 

 hardly have been worse, several gardens 

 in the north-west corner of the district 

 becoming practically closed towards the 

 end of July and in August. On visiting 

 these gardens in August it was found 

 that manufacture had come practically 

 to a standstill, leaf only being available 

 from a few acres of tea. " Gray blight " 

 in the case of one or two estates was 

 also greatly responsible for the closing 

 of those gardens, and "Red Spider " had 

 helped in the first instance to weaken 

 the bushes. 



The greater area of tea in that part 

 of the district is planted with a low jat 

 bush, which, as is well-known, is much 

 favoured and first attacked by the 

 blight. Those portions planted with the 

 indigenous and better jats were last at- 

 tacked, and in some instances blocks 

 have been left almost entirely free from 

 attack, although situated in the centre 

 of the affected area. This, without 

 doubt, points to the advisability of gradu- 

 ally uprooting the poor jat hybrid 

 bushes and by replanting with high- 

 materials. 



Effect of Scarcity of Labour. 

 The scarcity of labour in that part of 

 the district did not permit of " thinning 

 out " the bushes at the pruning season, 

 and it can, therefore, be easily under- 

 stood, when the nature of the growth of 

 China hybrid and low jat bushes is con- 

 sidered, that the mosquitoes had a sure 

 place of refuge in the heart of the 

 bushes where very little could get at 

 them to destroy them. The insects 

 sheltering in such a place would be en- 

 tirely protected from wind and i-ain. 

 Storms, which were this year of a very 

 mild nature, did not destory wholesale 



