332 



[April 1908. 



PLANT SANITATION, 



PRACTICAL REMEDIES FOR INSECT 

 PESTS. 



ByTH, Maxwell-Lefroy, m.a., > 



P.Z.S., 



Imperial Entomologist. 



The ultimate aim of the study of 

 destructive insects is the discovery of 

 some feasible method, whereby their 

 increase and destructiveness may be 

 checked and crops preserved from their 

 attacks. In such a quest, not only must 

 the habits and characteristics of each 

 individual pest be considered, but it is of 

 equal importance to take into account 

 the conditions under which the crop is 

 grown and the facilities there are for 

 adopting any method of repression. It 

 is probable that in India, the scientific 

 methpds that appeal to the skilled farmer 

 of European countries will be of little 

 value when applied to the conditions of 

 Indian Agriculture, and the best methods 

 that science reveals can scarcely be 

 regarded as suitable to the present pro- 

 blem. In very many cases, the habits of 

 a pest are such that practically nothing 

 is possible unless we can utilise the most 

 up-to-date and artificial methods. In 

 others, a weak point can be found in the 

 life of the pest when it can be success- 

 fully attacked by some very simple 

 means. Given some such simple remedy, 

 thorough co-operation in its application 

 over some area is usually also necessary, 

 and this is pei"haps to be obtained only 

 when an unusual abundance of a pest 

 awakes the ryot to the necessity of some 

 action and, with a little pressure, a fair 

 trial can be given to the remedy. Expe- 

 rience has shown that, for some pests, 

 there are such simple remedies as can be 

 applied by an individual cultivator, and 

 it is chiefly these I propose to discuss here. 



An instance that has already been 

 discussed in these pages (Vol. I, p. 58), is 

 the very simple method of checking the 

 stem-borer of cotton, where the withered 

 plants which contain the pest can be 

 removed and burnt with the pest in. 

 Theemerging beetle is not a wide-rang- 

 ing insect and is apt to confine its ravages 

 to a small area ; the destruction of the 

 withered plants in a cotton plot does 

 much to protect that particular plot, and 

 though joint action over a large area 

 would be far more effective, even a small 

 plot may be largely protected. 



The red bug of cotton is a pest that 

 yields to the simplest of all methods, 

 destruction by hand ; so also the very 



common dusky bug, which often swarms 

 in cotton bolls, can be checked by the 

 simple precaution of removing all the 

 bolls that are worthless at the same time 

 as the round ripe bolls are plucked. It 

 is unfortunately a general practice to 

 leave on the plant those bolls which 

 have been so damaged by bollworm as to 

 be not worth plucking ; the dusky bug 

 finds there a secure breeding place where 

 it may lay ito eggs, and where its young 

 can obtain food from the uninjured 

 seeds ; from these breeding places it 

 spreads to other bolls and in them it 

 sucks the seeds, rendering them useless 

 for sowing or oil-extraction. The re- 

 moval of all such bolls is a simple and 

 effective means of preventing the feed- 

 ing of this pest. In cases where dusky 

 bug is very abundant, a further simple 

 method is valuable ; the bug collects in 

 the bolls in great numbers and, when 

 disturbed, runs out and falls to the 

 ground. The greater number of these 

 can be destroyed by tapping the boll 

 while a pot of water with a film of 

 kerosene over is held below the boll ; 

 practically all the bugs fall into the 

 water and are killed, and an infested 

 field can be very rapidly cleared. 



Among the minor pests of cotton that 

 are occasionally very injurious is the 

 leaf roller, a green caterpillar that rolls 

 up the leaf into a funnel and lives inside. 

 This pest commences when the cotton (if 

 sown with the first rain) is about a month 

 old ; the rolled up leaf is very character- 

 istic and an infested plant has a peculiar 

 appearance due to the unnatural position 

 of these leaves. Every one of these 

 leaves can be picked off with the cater- 

 pillar in, and if the work is done early, 

 the first brood can be so thoroughly 

 checked that very little remains to be 

 done. If the first brood is missed, the 

 increase is so great that a vigorous crop 

 will be completely stripped later in the 

 season, and it then becomes a far harder 

 task. Were labour an expensive item, 

 spraying with an arsenical poison would 

 be the simple remedy, and both have 

 been in use on the Pusa Experimental 

 Farm. As it is, we have here a case that 

 particularly applies to our conditions, 

 one that is within the reach of any culti- 

 vator or Zamindar. 



A pest that is constantly reported from 

 cane-growing districts is the Moth-borer; 

 this pest was discussed in a previous 

 number of the Journal (page 97, Vol. I, 

 Pt. II.), and the principal remedy for it is 

 to cut out and remove all the shoots 

 which die in the young canes and which 



