138 



THE AGRICJLTURAL NEWS. 



April 29, 1911. 



INSECT NOTES. 



EXPERIMENTS WITH COTTON 

 STAINERS. 



A series of exijeriments to determine the effect on 

 the lint and seed of cotton, of the feeding of cotton 

 stainers (DyHdercun spp.),was outlined early in 1910 by 

 the Entomologist on the Staff of this Department, to be 

 carried out. in seveial of the cotton-growing islands in 

 the West Indies. 



The following notes gi\e the results of the experi- 

 ments conducted by Mi-. W. Robson, Curator of the 

 Botanic Station, Montserrat, and are taken from that 

 ofKcer's report, submitted to the Imperial Commis- 

 sioner of Agriculture. 



It will be seen that practically no effect on germina- 

 tion was produced by the feeding of the stainers on 

 seed which had been protected during growth, and 

 exposed to the feeding only after being harvested; while 

 the seed which was produced in bolls attacked during 

 growth showed a very small relative germinating power. 

 It will also be seen that the lint was affected to a very 

 serious extent where the stainers were abundant during 

 the development of the cottun. 



The experiments were carried out at Grove Station and 

 at Iveid's Hill, Montserrat. 



cROVE STATION. Fifty bolls were enclosed in muslin, 

 and developed in the middle of the .season (October to Novem- 

 ber). The seed-cotton was kept until the end of February 

 and divided into two lots, one of which was placed with cot- 

 ton stainers for about a week. The delinting of the seeds 

 was inadvertently omitted. Germination tests were made on 

 the seed of both lots, with the following results : — 



(1) Seed placed with stainers: average germination 96 

 per cent., on three tests. 



(2) Seed kept from stainers: average germination 96 

 per cent., on three tests. 



No examination of the lint was made in this case. 



A supplementary test was made subsequently on de- 

 linted seeds known to show a high percentage of germina- 

 tion, (1) placed with stainers, (2) kept from stainers. The 

 germination tests made on these seeds showed the following 

 results: — 



(1) Seed placed with stainers: average germination 91 

 per cent., on six tests. 



(2) Seed kept from stainers: average germination 92 

 per cent., on six tests. 



The cotton plots in Grove Station wore not infected with 

 cotton stainers until the beginning of this year (1911). On 

 the attack becoming general, tests wore made on seed devel- 

 oped previous to, and after, the attack, on the same strain of 

 cotton, with the following results: — 



(1) Seed obtained before the development of stainers: 

 average germination 89 per cent., on six tests. 



(2) Seed obtained after the attack of stainers was severe: 

 jiverage germination 20 per cent., on six tests. I am not of 

 opinion that the great difference in the results of this last test 

 is accounted for in the lesser vitality, generally, of seeds devel- 

 oped in the latter part of the season. 



uEiu's HILL. Samples of seed-cotton were collected on 

 this estate from .sections of the same field: (1) where cotton 

 stainers were abundant, (2) where no cotton stainers were 

 found. 



The lint from each of these samples was .submitted to 

 to the usual tests. That from the plant.s attacked by 

 stainers was so decidedly weak, as well as discoloured, as 

 to render it useless for shipping as first cotton. The 

 length of the staple and the percentage of weak fibre were 

 not notably different from those of the sample in comparison, 

 though there was a difference in the weight of the seeds, as 

 is shown by the following determinations: — 



(1) Seeds attacked by stainers: average weight of 100 

 seeds 9 52 grams, on ten tests. 



(2) Seeds not attacked: average weight of 100 seeds 

 114 grams, on five tests. 



One hundred of the seeds from the cotton attacked were 

 cut open, and forty-two were found to be decayed or shrunk- 

 en internally; while sixty of the seeds not attacked, which 

 were examined, were all found to be sound and plump. 



The average germination, on ten tests, of the seeds 

 attacked by the stainers, was 21 per cent.; while of the seeds 

 not attacked by the insects the average germination, on four 

 tests, was 94 per cent. 



While the results seem to .show that the stainer is 

 capable of doing serious damage to cotton, I am not of opin- 

 ion that it can be regarded as a serious pest in Montserrat at 

 the present time. It seems to become prevalent in certain 

 localities in particular seasons, but does not assume the 

 nature of a pest over large areas until after the bulk of the 

 crop has been gathered, that is after December of each year. 



A NOTE ON COCOA-NUT PESTS. 



In a number of the Agricultural News issued early last 

 year (see Vol. IX, p. 26), a short account of the insect 

 pests of cocoa-nuts appeared in the In.sect Notes. 



The following insects were mentioned at that time as 

 pests of cocoa-nuts in the West Indies: — 



The Bourbon scale (Aspidiotus destructor), the cocoa-nut 

 white fly {Aleyrodicus cocoU), the palm weevil [Rhi/nco- 

 phorus palmariim), (see also Agricultural JS^ews, Vol. X, 

 p. 122), all of which are of general distribution. 



The larger moth borer (Castnia lictis) was stated to have 

 occurred on cocoa-nut and other palms in Trinidad, and 

 Castnia daedalus in Surinam, while the cocoa-nut butterfly 

 (Brassolis aophorae) was reported as a pest in British fiuiana. 



Since the publication of the article mentioned above, 

 Castnia <laedalus has appeared in British Guiana attacking 

 sugar-cane (see Agricultural Neivs, Vol X, p. 122), and as 

 this insect is recorded as a pest of cocoa-nuts in Surinam, it 

 may be expected to attack the same plants in British Guiana. 



The Proceedings of the Agricultural Society of 2'rinidad 

 and Tobago, for February 1911, contained Notes on Some 

 Cocoa-nut Tests, by P. L. Guppy, in which it is mentioned 

 that the cocoa-nut butterfly {Jirassolis- sopliorae) occurs in 

 Trinidad, and that the caterpillars attack cocoa nuts in 

 the same manner as in British (iuiana. Another caterpillar, 

 the larva of a moth, lli/ptrcldria sp., also attacks the leaves 

 of the cocoa-nut in Trinidad. The caterpillars of this moth 

 (litter from those of Brassoiis sopltorae in not building 

 'nests', but resemble those of that species in being gregari- 

 ous. The attiusks of these two species produce a very simi- 

 lar appearance of the leaves. 



Mr. Guppy gives an account of the attack of a rhinoce- 

 ros beetle (Strategus anachoreta), on young cocoa-nut trees 

 in Trinidad, which is also additional to the posts in the list 

 given previous!)' in the Agricultural News. 



