10 



THE AORICULTURAL NEWS. 



Jasi AEY 4, 1913 



INSECT NOTES. 



THE BLACK WITCH OR TICK BIRD. 



'I'be black witch (C'rolop/i(i(/a ani) is an insect-eating 

 Ijird occurring from South America to the Southern United 

 States, throughout the Antilles, with the exception, however, 

 that it is not seen in the islands of Montserrat, Antigua, 

 iSt. Kitts and Nevis, in the British West Indies. Its occur- 

 rence in Dominica dates back only a very few years. 



This bird is known by a number of common names, 

 among which are the following: ani, black parrot, savannah 

 blackbird, tick bird, black witch, keel bill, and (in St. Lucia) 

 merle corbeau. 



The black witch is generally conceded to be a most 

 useful bird on account of its insect-eating habits; its food 

 includes many pests, and certain insects which are not gener- 

 ally eaten by birds. In Jamaica, the black witch has been 

 observed eating stink bugs* and cotton stainers: these are 

 :not often used as food by birds, on account of characteristic 

 offensive odours possessed by them. Ticks also form part of 

 •the food of the black witch, and on account of its tick feeding 

 habits it is called the tick bird in certain localities. As an 

 ^nemy of the insect pests of cotton, also, this bird is very 

 "«seful. 



As in the case of all insectivorous birds, however, this 

 one captures and devours beneficial insects, such as lady- 

 Ijirds and wasps, and it is probable that any beneficial as 

 ■^vell as injurious insects are eaten as opportunity offers. In 

 addition to ticks and insects, seeds and berries are also eaten. 



The question has recently been raised as to whether 

 -a useful purpose would be served by the introduction of the 

 "black witch into the island of Antigua. It would seem at 

 first sight that the introduction of a bird whose feeding 

 habits are known to be so useful could produce only beneficial 

 results, but so many instances are known where the 

 "introduction of a species of bird or animal into anew locality 

 has produced conditions other than those which werj sought, 

 that it is best carefully to consider whether there is another 

 aspect of the question. 



The habit of destroying ticks, stinking plant bugs and 

 cotton staintrs is one which entitles its possessor to 

 recognition, but the fact that beneficial insects are also 

 destroyed should be taken into account. There seems to be 

 no records of definite observations which would lead to the 

 forming of a conclusion as to the actual value of the black 

 ■witch in the Lesser Antilles and the possibilities of its 

 becoming a nuisance or even a pest in later years. 

 Predaceous beetles (lady-birds) and wasps (Jack Spaniards) 

 exert a considerable influence on the natural control of many 

 insect pests, and the destruction of these forms of insect life 

 might result in the increase of certain pests, especially the 

 .scale insects, which would not themselves be attacked by such 

 I bird as the black witch. 



It would be useful if planters and others who possess 

 knowledge based on observation and experience in those 

 localities where the black witch is well established, were to 

 record their o|>inions in this connexion, in order that the 

 matter may be carefully considered before definite recommenda- 

 tions are made; and any information on this subject would 

 be welcomed if forwarded to the Head Utiice of this Depart- 

 ment direct, or through the Agricultural Officers in the islands. 



♦Tht■^e lielong to the f:iiiiily Penlatoiniil.u', wliicli includi-.-^ 

 file typical plant bugs of which Ne::nru viriilula and JCdrsxa 

 iradllnhuiida are good e.xainples in the Lesser Antilk-s. The 

 iiionibers of this family possess a disagreeable wlour. 



EXPERIMENTS WITH HEVEA. IN CEYLON, 



Uulletin Xo. 1, of the Department of Agriculture,, 

 Ceylon, issued in September last, describes experiments oit 

 the tapping of Hevea rubber trees. These experiments have 

 been in jirogress for nearly four years, and Part III of the 

 investigation described in the publication under review, deals 

 with the etlect of different intervals between .successive 

 tappings. Seven rows of ten trees each were selected; the 

 trees were approximately twenty-five years old and had not 

 been tapped previously for some years. In the experiment 

 the trees Were all treated alike, except that each row was 

 tapped at a dill'erent interval of time. The average intervals 

 between successive tappings expressed in days, were as 

 follows: during 1909-10—1-4, 2 6, 4 0, 52, (5 7, V9, 91- 

 during 1911—0, 2.6, 3-7, 4,9, 62, 7 4, 8 9, for each of the- 

 seven rows respectively. 



The system of tapping is described as follows: 'The bark 

 to a height of six feet was divided into four equal areas, each 

 extending half- way round the tree. Each area was occupied 

 by three V-shaped cuts. The four areas were tapped ia 

 .succes-sion — first the lower half of one side followed by the 

 two upper areas in the same order,' 



As regards the method of tajjping, an interesting point 

 was the change from paring and pricking to paring only, made 

 in the middle of the experiments. All experiments of 

 a similar nature in Ceylon have pointed to the superiority of 

 the method of paring over that of combined paring and prick- 

 ing; and in the present experiments the trees showed signs of 

 injury up to the time of change of method which was believed, 

 to have been occasioned partly by the method employed. 



In the statement of results several important points are 

 brought to light All the tables show that an increased yield 

 is obtained from trees tapped at longer intervals, an increase 

 which becomes apparent after tapping has been continued 

 steadily for a considerable time. l!ow III,, which gave the 

 largest yield from the first area tapped, did not maintain its 

 high position as regards the tapping of the second and third 

 areas, even when allowance was made for a loss of a tree. 

 The largest total yield from the first area tapped was given 

 by row III,, and the largest yield per tapping, by row \'l. 

 A fairer basis of comparison is afforded, however, by taking 

 the yield per inch of circumference. It is then found that in 

 the case of area I there is an increase from row 1 up to row 

 III and thence a falling ofl" up to row VII,, whereas the 

 second area gave a steady increase up to row V. 



As regards the yield of dry rubber the annual amount 

 varied for 1-2 lb, with tapping at an interval of 9 days to 

 2'S.5 ft), with tappinj,' at an interval of 14 day. These yields 

 are, of course, extremely small considering the age of the 

 trees and the cause is supposed to be the close distance of 

 planting. 



Proceeding to the subject of overtapping,the complicated 

 nature of the physiological effect of paring is pointed out and 

 it is stated that even in the case of the most vigorous trees, 

 the period allowed for the first renewal should not be reduced 

 below four years. 'Die important point however, is that light 

 tapping steadily continued at intervals of from five to nine 

 days, causes trees, although old and very closely planted, 

 to give a greatly increased yield per tapping. 



The bulletin under review concludes with the following 

 summary; — 



'(1) When Hevea rubber trees were tapped at diflerent 

 intervals on the system here described, the yield //e;- lappitig 

 increased with the increase of interval up to an interval of 

 about a week between aucceasive tappings. 



