MAViJ, 3887.3 



"tm TROPICAL AGRtCULTURISt. 



759 



THE NEW ENEMY OF COFFEE:— GEEEN 

 BUG. 



[" OBSERVATIONS ON THE GBEKN SCALE BUG IN CONNEC- 

 TION WITH THE CDLTIVATION OF COFFEE, " BY E. 

 ERNEST GREEN, PUNDALUOYA — PUBLISHED BY THE 

 CEYLON GOVERNMENT.] 



This little pamphlet has hitherto — somewhat 

 unaccountably — escaped our notice. It has been 

 compiled at the request of Government by Mr 

 E. E. Green, whose efforts have resulted in a very 

 interesting life history of the most recent pest 

 which has affected coffee cultivation in Ceylon, and 

 — like the locusts that ate up all that the hail had 

 left — has devoured all that was left by the leaf. 

 disease in the northern districts, and to a con- 

 siderable extent in other coffee-growing portions of 

 the country. 



This scale bug is named Lecanium viride, to 

 distinguish it from the Lecanium coj'ece and the 

 Lecanium nigrum, which constituted the old black 

 bug known in Ceylon from the very early days 

 of coffee planting. The presence of all these scale 

 bugs is alike followed by the black fungoid growth 



which induced the commonly-used term black 

 bug. Mr. Green gives us a description of the L. 

 viride, and compares it with the other species, 

 in size and appearance, and adds a plate of 

 beautifully executed coloured figures both natural 

 size and highly magnilied. The greater destruc- 

 tiveness of the green bug compared with the others 

 is explained by the difference in its reproduction. 

 Impregnation of the female of the brown and 

 black Lecanium is direct — the male insect being 

 a small winged insect, and "the eggs are not 

 hatched until after the death of the parent insect 

 whose body shrivels internally whilst the external 

 scale becomes firmly attached to its support and 

 forms a protection to the eggs and young larva." 

 This was well-known to all our planters but the 

 modus generandi of the green bug is very different 

 and will, no doubt, be new to many of those who 

 have been accustomed to consider the old and 

 new bug as one and the same insect. 



" The eggs ot Lecanium viride are hatched under 

 the body^and during the life of the parent insect, 

 which possibly produces several successive broods. 

 (Since writing the above I have found immature 

 eggs inside the body of the parent insect after 

 the first brood has been hatched). This may 

 account for the greater numbers and destructive- 

 ness of the species under notice. The eggs which 

 vary in number, but are seldom more than 

 twenty, are hidden by the body of the living 

 insect, and are hatched in that position. The 

 young larvte is only visible to the naked eye as 

 a minute speck. It is very active and moves 

 freely from kaf to leaf deserting the old, 

 and spreading over the youug shoots where it 

 finally settles itself, and soon developes the scale 

 characteristic of the mature insect. It is 

 ill this early larval stage, probably that the pest is 

 chiefly propogated, as besides its own powers of 

 locomotion, it is liable to be transpoi'ted by wind, 

 in the feathers of birds, and upon coolies' clothing. 

 The young insect (as I have proved by experiment) 

 will live for many days without food, and might 

 easily be unconsciously transported from one dis- 

 trict to another over considerable distances." 



Here then we have an explanation of the extreme 

 apidity with which the green bug has spread over 

 tbe country aocl the estraQr^ioary d^gtfuctiyenedci 



with which its career has been characterized, render- 

 ing it by far the most formidable enemy with which 

 the planter has had to contend. Mr. Green puts for- 

 ward a supposition as to the impregnation of the 

 female insect which we recommend to the attention of 

 entomologically inclined readers. We merely quote 

 the paragraph with the remark, that as far as can 

 be learned from the text — the only reason he has 

 to give for adopting it as probable, is the fact of 

 the male insect being at present unknown : — 



"It is probable that the insects now existing 

 though externally resembling the female form, are 

 asexual, and that their broods are produced by 

 the phenomenon known as ' Fartheno Genesis,' by 

 which several successive generations are fertile 

 without the aid of the male element (as is known 

 to occur in the development of aphis and a few 

 allied insects). Professor Huxley states that the 

 number of successive broods has no certain limit, 

 but is, as far as we know at present, controlled 

 only by temperature and the supply of food." 



"Effect of the green scale bug upon coffee " is 

 unfortunately too well-known in Ceylon to need 

 reproduction in our columns. "The results of 

 manuring and liberal cultivation " may be con- 

 densed into a single sentence "manure has been of 

 use only where the trees have not quickly suc- 

 cumbed to the efl'ect of the bug ; on poor soil the 

 tree seems to be permanently injured upon the first 

 appearance of the pest — and manure entirely fails 

 to revive them." 



" Will trees badly attacked by the bug, event- 

 ually throw it off and survive ? It is difficult to 

 obtain reliable information upon this question ; but 

 there seems to be no doubt that in some few cases 

 the pest has disappeared from once badly infested 

 coffee." Here a tew facts are mentioned as proof 

 which need no comment and it is when we come 

 to "proposed remedies" that our readers will be 

 interested. Writing of the remedies for the old 

 bug, Mr. Green says that maana grass has no 

 effect ; caustic lime is equally useless, the same in 

 regard to wood-ashes. If the caustic lime could 

 possibly be applied to every insect it would prove 

 fatal, but that is an impossibility. Acting on a 

 suggestion of the late Mr. Neitner in his " Enemies 

 of the Coffee Tree," that tar applied to the roots 

 and "taken up into the system of the tree throws 

 off the bug." " 1 have tried the solution of Phenyle 

 brought into notice as an insecticide " a few years 

 ago. It is one of the extracts of coal tar, and 

 probably contains most of its active properties in 

 a form that can be more easily taken into the 

 system of the tree. The mixture used consisted 

 of one desert spoonful of phenyle to two quarts 

 of water. The soil around the root of the tree 

 was thoroughly broken up with a digging fork, 

 and the liquid applied from an ordinary watering 

 can. My experiment was limited to a single tree, 

 and scarcely a sufficient time has elapsed to judge 

 of its success. But it has seemed to me that the 

 pest upon that tree has been gradually disappear* 

 ing although the surrounding trees have not altered 

 their condition. Dec. 31st. — after an interval of a 

 month I now find that this tree has entirely thrown 

 off the bug, although on neighbouring trees the pest 

 has rather increased than otherwise." 



This is so far satisfactory as phenyle could be 

 obtained in large quantity at a very small cost 

 and we should like to hear more of this ex- 

 periment and of similar ones on a larger scale. 

 Mr. Green has also heard of the success of an 

 application of Schrotky's cure for leaf dis- 

 ease 15 per cent carbolic lime, 3 bushels to an 

 acre, in ten days the bug turned white and died, 

 and after a months the colee ig looking remark' 

 ably bealtby. 



