394 



THE AGRICULTURAL NEWS. 



December 9, 1911, 



INSECT NOTES. 



THE COTTON STAINER IN 

 TRINIDAD. 



The Board of Agriculture, Trinidad, has recentl}' issued 

 two circulars, prepared by Mr. P. L. Guppy, Acting Ento- 

 mologist, providing information as to the life-history, habits 

 and control of the cotton stainer. 



The following notes are taken from the circulars and 

 should be of interest to cotton growers in the West Indies, 

 especially those which refer to the methods of control of the 

 pest. 



The cotton stainer of Trinidad is Dy^dercus hoivardi (see 

 Fig. 14) and is perhaps the worst pest of cotton in that 

 Colony. The life-cycle, from the time the egg is laid 

 until the development is completed and the adult insect 

 appears, occupies a period of from thirty-six to forty-two 

 days, divided into five stages — the egg and four larval 

 stages — at the end of each of which the developing insect 

 moults, or sheds its skin. 



/^\ 



fic. 15. Till; TiMNiii.vK C'liTioN Stainer. 



{Di/sdcrci'it lidwnrdi, Rallou.) 



Three times natural size. 



The cotton stainers are gregarious in all the larval stage.s, 

 and in the adult condition. The bright-red colours of the 

 young stainers make them conspicuous objects, especially 

 when they are congregated in masses within the open bolLs, 

 where they feed. The adult insects, which are less Iirightly 

 coloured, and possess yellowish wings with black tips, are to 

 l>e found in the same' places as the young. 



The cotton stainers feed on the seed in the liolls, and 

 stain the lint with their excrement, the injury to the lint 

 resulting both from the feeding of the insects and from tlie 

 staining of the cotton. 



In hot, sunny weather the.sc insects are very active; 

 but in the early morning, in the evening, and on dull or 

 rainy days they are sluggish in their movements. The 

 adults are capable of long-.sustained flight; but they are not 

 very ready to avail them.ielves of this ability, and as a con- 

 sequence do not often use their power of flying for the 

 purpose of invading 'new territory, as long as their food 

 .supply continues in the old. 



The suggestions for the control of the cotton stainers 

 include the old methods of hand collecting and traps, and in 

 addition a new form of trap devised by Mr. Thomas Thornton 

 of Tobago. 



This last method consists of the use of stained or 

 damaged seed-cotton, tied into balls the size of a man's fist 

 and hung, by means of a bent wire, on the branches of the 

 cotton plants. The stainers collect on these for the purpose 

 of feeding, and may lie shaken off into a vessel containing 

 kerosene or crude petroleum and water. The balls are then 

 again hung on the plants to attract a further lot of stainers, 

 when the process of collecting maj- be repeated. It should 

 be borne in mind, however, that the oil should not be 

 allowed to come into contact with the trap balls, as the 

 odour would prevent the stainers from returning to them. 



These traps .should be visited every day, and the stainers 

 collected. When the insects are few, the traps need not be 

 placed close together, but when they become more abundant, 

 the number if the former should be increased 



The older methods of collecting from the plants, and 

 trapping by means of heaps of cotton seed on tiie ground, 

 are also described in a modified form. 



It is recommended that all leaves, trash, etc., on the 

 ground in the cotton fields should be carefully cleared away 

 from beneath the plants, and left in small heaps in the spaces 

 between the rows. Into each of these heaps a small handful 

 of cotton seed is dropped, and each heap is then covered 

 with a broad leaf, such as that of certain palms. 



The stainers on the plants are collected liy being jarred 

 or shaken into vessels of oil and water. Many of those which 

 tall to the ground will take refuge in the heaps of trash, and 

 finding food there, are likely to remain. The trap heaps 

 should be regularly visited, and the stainers which are 

 collected there killed by means of hot water or kerosene. 

 The heaps should then be stirred so as to present a fresh 

 surface, and clean cotton seed added. The covering leaf is 

 replaced, and the trap is ready again. 



After the cotton crop is finished and the old plants have 

 been removed, many stainers will find their way to these 

 traps. After an interval of two or three days, to allow as 

 many of the insects as possible to congregate, the traps 

 should be completely burned. 



By following this system of trapping and collecting, 

 and l)y practising clean cultivation, cotton planters should 

 be able to reduce the numbers of stainers very considerably. 

 Attention is specially directed to the necessity for destroying 

 all wild food plants of the pests, thus depriving them as 

 much as possible of the means of surviving during the interval 

 between the close of one cotton-growing season and the 

 beginning of the next. 



The Froghopper of the Sugar-cane.— The 



Barliiidos Government has issued an Order dated Novem- 

 ber 10, 1911, under the Trade Act (1910-15, Sections 45 

 and 4C>), prohibiting the importation of sugar-canes from 

 Trinidad and I'.ritish Guiana, except that sugar-cane cuttings 

 intended for propagation may be imported under a special 

 licence from tlu^ Governor-in I'.xecutive Committee, to be 

 obtained through the Superintendent of the Local Depart- 

 ment of Agriculmre. 



The serious nature of the frog-hopper attacks in 

 Trinidad causes planters to be apprehensive as to the 

 possibility of the post being introduced, and this Order is 

 intended to prevent this occurrence. 



The Order gives the Superintendent of Agriculture 

 power to direct the destruction of any sugar-cane cuttings 

 imported in violation of its provisions. 



