3 28 



THE TROPICAL AGRICULTURIST. 



[October i, 1884. 



3. Helopeltis itself belongs to the true Hemiptera, 

 being a member of the tribe Cuspida all of which are 

 destructive to plants (one especially so to raspberry fruits) 

 and are partly characterized by their comparatively active 

 running habits of the geuus, several species have been de- 

 scribed by naturalists of which the present insert //. Autniui 

 Lynt, is the best known. In the adult state this can 

 scarcely be mistaken for any other insect, and may be 

 recognized by the following description. The narrow body 

 is less than J inch (6 mm.) in length, but the greyish 

 wings project beyond the abdomen and thus increase the 

 lengtU to nearly J inch (8 mm.); the thorax is brownish-red 

 in colour and ends in a slender red neck, from its centre 

 arises the singular erect rigid pin-like process which gives 

 the gonus its scientific name (hilos — a nail). The head is 

 small and black, and a characteristic feature are the 

 antennas quite g inch (10 mm.) long spreading, 4-jomted, 

 and curved. On turning the insect over, the abdomen is 

 seen to be black, but in the female this is crossed about 

 the middle by a broad band of white. The formidable 

 beak or proboscis, fully 2 mm. long, can be seen beneath 

 the thorax, to which when not in use it is pressed. The 

 insect is long-legged and active and can fly well, but so far 

 as I have seen does not make any long flights. 



■i. Before arriving at the imago state, the Helo- 

 j;/ti.< passes through several stages, but the changes 

 (as in all the bugs) are not so complete as in most 

 insects. When first, hatched it' is about 1-24 th inch 

 (say 1 mm.) long, pale yellowish olive in colour and 

 semi-transparent, the eyes and some internal parts show- 

 ing red. During its progress through the larval stage it 

 sheds its skin several times, and the little empty sloughs 

 are commonly found on the cacao. The olive colour is 

 maintained through these changes, and the insect is easily 

 recognized by the thoracic spike which is soon developed, 

 the long antennas, and the long legs which raise the body 

 well otf the surface; the abdomen is soft and pointed and 

 turned up at the end. .Rudimentary wings are present in 

 the pupal stage but are not matured for use until the 

 fiual change from this to the perfect insect. Though thus 

 unable to fly, these immature creatures run about pretty 

 briskly and their appearance is decidedly ant-like; appar- 

 ently their whole existence is passed on the cacao plant 

 where they were born. 



5. I regret that my opportunities and leisure have not 

 permitted me to trace out the whole life history of the 

 insect. I do not know the time occupied from egg to 

 imago nor how long the latter lives. I find that the fem- 

 ale contains from S to 12 eggs, large for the size of the 

 insect, and of a peculiar long flask shaped form provided 

 at the truncate end with two filaments half its length. 

 I have not succeeded in seeing the actual deposition of the 

 egg, but I have detected two in situ, one attached to a 

 punctured cavity in the leaf-stalk and the other in the 

 tender shoot at' the foot ot a leaf-stalk ; these were milk 

 white with a tough skin. Atter a careful search I have not 

 discovered more than these two, and my knowledge on the 

 point is thus very defective; so far as it goes it corre- 

 sponds with that of Van Gorkom in Java who says 

 that, (in Cincknna) the eggs are laid in the ends of twigs 

 and in leaf-stalks but are quite hidden and very diffic- 

 ult to find. 



6. The little msects commence to suck the plant "at 

 once, and they continue to do so throughout their lives. 

 Apparently they especially feed at night, and the amount 

 of iujury a single one is capable of effect! g can he seen 

 by any one who will place one in a cage with a fresh 

 shoot for a night and examine the shout in the morning. 

 The underside of the mid-ribs of the very young leaves 

 is also a favorite position for the punctures. It may be 

 presumed that the perfect female insect does some damage 

 also by the deposition of the eggs. 



7. The nature "f the injury effected on the cacao is 

 primarily a direct loss of sap. This nutritive fluid is 

 drawn out of the delicate tissues of the newly formed 

 shouts and leaves by the sucking action of the long b. ak 

 of the insect. The immediate result is a collapse of the 

 cells; they become shrunken and brown, aud the appar- 

 enf external effect is a depressed or sunken circular, or 

 oval brownish stain at the position of every puncture. 

 These are often in such proximity that the stains co- 

 alesce, with the result that the whole shoot is mottled 



with brown blotches of irregular form. The injured tis- 

 sues soon die .and are found after a yvhile to have be- 

 come black and rotten. A hindrance to the passage of 

 the sap up the shoot occurs, the tips are seen to fail 

 and droop, and the leaves to become puckered and 

 stunted and irregular growth is all that is made. In worse 

 cases the shoot withers away at the tip ami the whole 

 " dies back" to a greater or less distance. The tree soou 

 endeavours to put out a fresh crop of shoots, and if 

 these be again attacked, they share the same fate. At 

 length after repeated attacks tlie smaller woody branches 

 also die and only the main branches remain. 



8. It was this ''dying back" that first attracted the 

 attention of the superintendent of the estates in question iu 

 Oct. 18S3 ; and iu December he forwarded to me some of the 

 affected shoots for an opinion, being himself under the 

 impression that the trees were ■ " cankered." I at once 

 informed him that the injury was due to a sucking bug. 

 Since that time many successive crops of young shoots 

 have been produced and destroyed, and though a watch 

 was kept for insects, none could he detected doing the 

 mischief. One of the small leaf-hoppers common in cacao 

 (allied to aphrophora, the "euekoospit" of England) being 

 the most abundant insect to be found, was fixed upon 

 as the probable culprit aud was supposed to effect his 

 depredations at night. 



9. On my first visit I found but few fresh shoots on 

 the tree, owing to the prolonged drought, the bad effects 

 of which were clearly apparent, but what there were in 

 the area affected bad mostly been attacked, were badly 

 spotted and evidently doomed to "die back." Though I 

 was convinced this was the work of Helopeltis, yet a care- 

 ful search with the superintendent revealed but a very 

 few of them (in several stages), though insects of various 

 other kinds, including the suspected plant-hopper, were nn-re 

 numerous. The difficulty, however, of detecting the immature 

 Helopeltisis well-known, so much so that both in Javaand As- 

 sam as now here, it is difficult for planters to believe that 

 such serious mischief is wrought by a foe so nearly in- 

 visible. I therefore requested the superintendent to initiate 

 syste -atic catching of this insect, which he consented to 

 do. The results obtained corroborated my belief that 

 Helopeltis is really far more abundant than it appears 

 to be. During the first two days, indeed, though six coolies 

 went over 220 acres, only 311 specimens resulted: but so 

 soon as the boys learned how to find the insect, the num- 

 bers increased. Thus by the end of ten days 2,011 had 

 been bottled, and in the forty-one days ending with 

 August 31st, as many as 25,000 individuals (the greater 

 proportion being immature ones) had been captured ami 

 destroyed, I believe that the cause of the " disease" is uo 

 longer a matter of doubt iu the mind of the superintendent. 



10. With regard, however, to the -actual condition of 

 the cac^o trees on these estates, I should not be fully 

 carrying out your request, if I were to omit to express 

 my conviction that the damage done by Helopeltis iu 

 ihis locality has been rendered considerably more serious 

 by certain local circumstances. There is no occasion for 

 me to insist further on the generally recognized need of 

 shelter from wind iu the cultivation of cacao, but I may 

 say that a dry wind is much more destructive when it 

 passes over tender shootsalready debilitated and rendered 

 flaccid by the abftraction of sap and the exhaustion of 

 their tissues; such become quickly desiccated and destroyed. 

 So too, a period of drought, such as has been experienced 

 this year, will have a more disastrous effect under the 

 same circumstances than under ordinary ones. And these 

 adverse conditions have operated with unusual force on the 

 estates under consideration from the following causo ; a heavy 

 shade of large trees which formerly covered them has been 

 completely cleared away. Thus the cacao, accustomed to 

 shade and shelter, was suddenly exposed to the full effects 

 of sun and wiud. I have elsewhere expressed the opinion 

 that iti the moister districts of Ceylon shade is not required 

 for cacao aird need not be supplied, but it is a different 

 thing to suddenly deprive plants of conditions to which 

 they have become accustomed, and especially so in a dry 

 district. Moreover, shelter can never be dispensed with. 

 .Thus though I regard the attacks of the bug as the origin 

 and snurce of the mischief. I cannot but believe, that the 

 damage has been much aggravated by the exposure of the 

 trees, after long protection to drying yvinds and sunshine. 



