194 A. D. PEACOCK — ENTOMOLOGICAL PESTS 



Hence it is probable that a new generation may be full-grown in about nine to 

 ten weeks. 



The stainer is the worst pest of Southern Nigerian cotton, and does an 

 immense amount of harm both to the seed and to the lint. The stained condition 

 of the cotton in the native markets in the Western Province, and especially the 

 cotton gathered late in the season, is striking. At Illushi, on the Niger, where 

 the native Ishan cotton is ginned, the lint seems much cleaner. It is regrettable 

 that no figures are available to show the exact proportion of stained to unstained 

 in imported and indigenous cottons. From observations on imported cotton at 

 the Agricultural Station, Ibadan, it may be put, very tentatively, at 20 per cent. 

 Native cotton is not so badly stained. 



It has yet to be demonstrated for Southern Nigeria that it would pay the 

 native (and the European buyers and manufacturers) to take increased care in 

 the production of cleaner cotton. 



The problems of treatment are : — 



(1) What preventive measures can be adopted to prevent the stainers from 



breeding among the cotton ? 



(2) What measures can be taken, once the stainers are present ? 



(3) What is the practical value of such measures ? 



A statement of experiments may be given first. The period and opportunities 

 of the tour were rather unfortunate for the carrying out of work on a large scale 

 and at the best time, which is from the end of October onwards. 



Experiments. (1) An experiment was performed at the end of November 

 1911, among the " Georgia " cotton, to test the value of cotton seed and pressed 

 seed as baits. Small handfuls of bait were placed at intervals of about six feet 

 between the drills. After a few days a few young stainers were found swarming 

 about one heap of bait. Evidently some adult had laid eggs among it. The 

 results of a longer period were not satisfactory. 



f\ (2) A quantitative experiment was made on 14th December 1911, among 

 late ripening Nyasaland Upland Cotton. The objects were : — (a) to find the 

 effect of bait ; (b) to find the approximate amount of labour and material required 

 to carry out the experiment. The land had been well cleared and the furrows 

 were two feet wide. A large number of patches of weed had sprung up, however, 

 and were acting as breeding and sheltering places for the stainers. The bait 

 was laid in quantities — about as much as could be taken up by two fingers and the 

 thumb — on large cotton leaves at intervals of about six feet. The rows were 

 laid with cotton seed and pressed cotton seed alternately. The bait served the 

 purpose of enticing stainers, but the collecting of them could not be carried out 

 owing to the writer leaving the plantation on tour. 



From the results obtained the following estimate was arrived at : — To clear 

 and lay traps on 10 acres of cotton would occupy 25 labourers and one head-man 

 for one day of 8^ hours. This would cost £l for labour, and the cost of 

 collecting the stainers would be about 10s. The process would have to be 

 performed twice, giving a total estimated cost of £3 for the 10 acres. 



Preventive Measures. The imported American and Nyasaland cotton plants 

 are smaller than the indigenous Meko or Ishan plants and more easily dealt with. 

 Constant field work has fully demonstrated the great importance of keeping the 



