274 



THE AGFJCULTLFEAL NEWS. 



September 1, 1009 



worm, the leaf-blister mite, cut worms, the red maggot 

 and grasshoppers ; the second comprises scale insects, 

 plant lice and cotton stainers. Detailed information con- 

 cerning the appearance, life-history, and modes of doing 

 harm of these, as well as remedies for them, can be 

 found in the Arjriculturnl N'ews, Vol. VI, No. 141, and 

 in the articles which frequently appear under (he head- 

 ing 'Insect Notes'; in the West Indian Bullitlit, 

 Vols. IV, p. 2G8 ; VI, p. 123: IX, p. 235; and in 

 Pamphlet No. 45 of the Department Series, entitled 

 'ABC (if Cotton Flantiv;/', to all of which special 

 reference is made. 



All the pests included in the fi:'st kind, with the 

 exception of the leaf-blister mite and the red maggot, 

 can be best controlled by stoinach poisons, the most 

 useful of which has been found to be Paris green ; 

 therefore there should be a btock of this substance on 

 hand at the beginning of the cotton-growing season in 

 order that it may be made use of as soon as it is 

 required. For caterpillars and grasshoppers, the nii.x- 

 ture of it made with lime is dusted on to the leaves, 

 but in the case of the latter insect, if it attacks the 

 plants when they are very young, poisoned baits 

 composed of young grass on whicii the insecticide has 

 been sprinkled should be provided. Such a bait is 

 also useful in the case of cut worms, which eat 

 through the .stems of the very young plants : a more 

 attractive fine, consisting of bran and Paris green 

 mixed to a mash with molasses and water, is however 

 generally used. The leaf-blister mite and the red maggot, 

 the latttr of which seems to have reached its chief 

 importance, as a pest, in Barbados, cannot be controlled 

 by stomach poisons. They are best kept in check by 

 preventive measures, these being, respectively, the 

 destruction of old cotton, and the exercise of care, 

 esijcciaily during cultivation, that the plants are not 

 wounded in any way. As a remedial measure for the 

 former, dusting with lime and sulphur has been found 

 succe-ssdd ; the latter may be kept in cheek by the 

 removal of affected branches and of dead and dying 

 plants. 



Of the second kind, namely, those which pierce the 

 tissues of the plant in order to obtain food, and which, 

 therefore, arc not controllable by stomach poisons, the 

 scale insects are generally the most likely to interfere 

 with its growth. These, together with the plant louse, 

 are best kept in check by the use of contact poisons, 

 such ;is kerosene emidsion and whale oil soap in a spray. 

 The preventive method, that of burning old cotton, is 

 by far the most satisfactory, however, for the former. 

 The cotton stainer may be shaken off tiie plants into 

 a tin containing water covered with a little keropene, 



or traps of heap^ of cotton seed may be laid for it, which, 

 when they have collected a sufficiently large number of 

 the insects, are soaked with kerosene and burnt. 



The cotton worm, grasshopper, and leaf-blister mite 

 interfere with the nutrition of the plant, the first two 

 by eating the leaves, either wholly or partially, the last 

 by causing .such distortion of them, especially when 

 they are young, as to cause a serious loss of their power 

 of making plant food. Scale insects, plant lice and 

 cotton stainers suck the juices from the plant, and thus 

 rob it of food which is necessary to growth. The last, 

 at any rate in the West Indies, does not cause much 

 damage in this way; it is chiefly objectionable because 

 it stains the cotton in the boll with its excrement, or 

 may cause similar damage by being crushed during 

 ginning. The red maggot, which is really the larva 

 belonging to a fly of the family of the gall gnats, gets 

 beneath the bark by means of wounds, and feeds on the 

 cambium layer. As this is composed of thin-walled, 

 quickly growing cells, on the formation of which the 

 thickening of the stem depends, any attack in which 

 this is severely implicated will speedil}' load to the 

 death of the whole plant. Finally, the damage done 

 by cut worms is irreparable, as far as the attacked 

 jjlants are concerned ; but as this attack occurs only 

 when the plants are very young, the evil may often 

 be remedied by supplying dead holes. 



It must not be forgotten that all these pests have 

 their own enemies which keep them in check, and 

 that it is only when the rate of survival of them is 

 increased by the provision of an unnaturally larn-e 

 amount of the plant on which they feed, that the 

 balance of nature is upset and the parasites are not 

 produced sufKciently (juickly to deprive the pests of their 

 abnormal advantage. In time, however, if there are 

 no untoward circumstances to prevent it, the very 

 fact of the increase of a pest will lead to a similar 

 increase in the numbers of its parasites, and the balance 

 will be restored. The best known of the insects that 

 arc useful to cotton growers in the West Indies, in this 

 way, are two very small hymenopterous insects 

 {Trwhogramnm yretiosa and Chalcis annidaim) 

 which respectively prey on the eggs and larvae of the 

 cotton worm, the 'Jack Spaniard ' (wild bee, of Barba- 

 dos) which is also inimical to this pest, and the lady- 

 birds and lace-wing tly, or aphis lion, which are the 

 enemies of the plant louse. All these should, of course 

 be encouraged and nerer destroyed\w-hen it is possible 

 to avoid doing so. 



Enough has been said to indicate the serious 

 damage that can be etfectcd by these pests, the neeess- 



