264 



THE TROPICAL AGRICULTURIST. 



[October i, 1884. 



6. Iihinophlia sp. 



7. Serica sp. 



8. Apoyonia (or uew genus?) 



9. Adoretus sp. 



10. Ancylonycha sp. 



11. I cannot find. 



12. Probably same as No. 10. 



13. Ancylonycha sp. (the "Maskeliya chafer.") 



14. Ancylonycha sp. 



15. Adoretus sp. 



16. Apoyonia sp. 



17. New genus allied to Apoyonia. 



18. Anomala sp. 



19. Adoretus sp. 



20. Adoretus sp. 



In addition to the foregoing there are many species of 

 Celoniadce, a few stag-beetles, a Buprestis (Campsosternus 

 Templetonii, Westwood), one species of Passalida, sundry 

 Histerida-, Tmelmonidep, Scaraha-idtr, &c. The Celoniadce 

 are probably indicated as "carpenter beetles" in Mr. 

 Brame's letter, but the term more correctly belongs to 

 Lonyicorna, which are not represented. 



Dealing with the subject purely as " grub," it appears 

 to me that with regard to the insects forwarded the 

 interest is specially centred in the numbered species, for 

 all or nearly all of them are close allies of the notorious 

 Melolontha vulgaris (the common European cockchafer). 

 The larva; of stag-beetles feed on the wood of trees, and 

 from the size of those sent it is probable these were 

 bred in some large tree near the coffee plantations, 

 rather than in the coffee plants themselves. The Buprestis 

 may have lived as a larva in the stem of the coffee. 

 The larva; of others feed in dung or in decayiug vegetable 

 matter. The Celoniadce may or may not damage the 

 coffee roots as larva;, and it may be assumed as certain that 

 the beetles damage the flowers by feeding on them and 

 preventing fructification by destroying the stamens and 

 pistils ; therefore it is essential that perfect beetles 

 should be collected and destroyed when the plants are in 

 flower. 



Returning to the chafers, which no doubt are 

 destructive both as larva? and perfect insects. It 

 may be taken for granted that any larva that eats 

 the young roots of a plant must damage that plant, 

 and if the larva? are in sufficient numbers, and the 

 attacks be persistent, the plant must succumb sooner or later. 



And this brings me to the points I., II., III., and IV. in 

 Mr. Christie's report 



In point I., a distinct statement, that the ravages of the 

 " grub" do cause the " emaciation" of the coffee trees, is 

 asked for. Here I would call special attention to the 

 paragraph almost immediately preceding marked*. The 

 insects accused of doing the mischief are most nearly 

 related to the European cockchafer. The larvre (or " grubs") 

 of these insects feed on the roots of plants, and the 

 very circumstantial evidence afforded by the reports of 

 Messrs. Braine and Christie, and Mr. Haldane's pamphlet 

 ("All about Grub") can, in my opinion, leave no doubt 

 that the Ceylon chafers conform to ' the habits of their 

 European allies. [In connection with this a statement of some 

 importance will be found (vide post) in the consideration 

 on points III. and IV.] Then there is a " suggestion" 

 put forth by some planters (alluded to also in Mr. Haldane's 

 pamphlet, p. 11) that the grubs do not attack healthy plants, 

 but only those that are sickening from some other cause 

 or causes. In the case of beetles, the larva; of which 

 bore into or feed under the wood or bark of trees and 

 shrubs, this "suggestion" would probably prove abundantly 

 justifiable. But we have to deal here with quite another 

 method of attacking the plants. The tribe of cock- 

 chafers are root-feeders in the larva? state, and ac- 

 cording to all previous evidence they prefer plants in 

 which the roots are succulent and in a presumably general 

 healthy condition. Therefore, I would rather assume that 

 plants attacked by " bug" or fungus may have already 

 had their constitution injured by the unsuspected presence 

 of " grub" at the roots. Different groups of insects 

 have distinctly different proclivities in their tastes, and 

 the conditions that might Ibe eminently favourable for one 

 might be equally unfavourable for another. 



Point II. concerns the probablo duration of the active 

 life of a chafer, and it is stated that some plautcrs 



maintain that a female chafer flies for one evening only. 

 This latter opinion may be dismissed as absurd, and it 

 is probably based on some idea connected with the- life 

 of a May-fly (not "May-bug") and incorrect even for that. 

 I think it probable that a chafer may exist as a free-flying 

 perfect insect for weeks. [I used the term free-flying be- 

 cause, in the European cockchafer, there is evidence that 

 the transformation from the pupa to the perfect insect 

 ordinarily takes place long before the latter emerges into 

 open air.] Formerly it used to be considered that when 

 insects once paired, the male died immediately, and the 

 female followed so soon as her eggs had been deposited. 

 This has been disproved in so far that both males and 

 females may pair several times, and with different partners, 

 and that both sexes sometimes live long after the pro- 

 creative business of their lives has finished. A far more 

 serious consideration is the duration of the insects as 

 " grub." This the parties interested in Ceylon must decide 

 for themselves by observation and experiment. With regard 

 to the smaller chafers (Ancylonycha, Sic.) I should think 

 that one year would suffice for the complete life-cycle 

 from the deposition of the egg to the death of the beetle 

 produced therefrom. We here, in England, would be 

 apt to conclude that a much longer period would be 

 necessary in the case of the " big'patana cockchafer " (Leuco- 

 pho/is); but on this point Mr. Haldane, (who has care- 

 fully read up the literature at his command, and judiciously 

 reasoned thereon,) points out that although more than 

 three years may be necessary for one cockchafer to go 

 through all its transformations, the same rule may not apply 

 in Ceylon where there is practically no dormant season, and 

 that there the transformation may perhaps be effected much 

 more rapidly. 



Points III. and IV. may be taken together. They are 

 the most important and, at the same time, the most diffic- 

 ult to consider. We are not dealing here with a special 

 insect attacking a special plant. The Phylloxera of the 

 vine may be taken as an example of the latter class, and one 

 that should be the more easy of attack, because all its life is 

 practically passed in one condition underground. We have 

 to deal here with enemies the larvre of which will probably 

 feed ou the roots of any plant, and which in the perfect 

 state can shift their quarters at pleasure. 



Here I would first of all call attention to one special 

 point. I surmise that in the coffee plantations no under- 

 growth of grass or other herbaceous plants is allowed to 

 exist. A distinct understanding on this point appears to 

 me to be of very great importance. The grubs of the 

 European cockchafer and its allies do not as a rule feed 

 ou the roots of trees and shrubs, but on those of grass 

 and herbaceous plants. Supposing a certain amount of 

 analogy to exist in the habits of the Ceylon species 

 (and analogy in habit should always be suspected in 

 closely allied insects), the keeping of the plantations 

 perfectly free from weeds and undergrowth should be of 

 paramount importance. Judging from analogy, the grubs 

 should prefer the roots of the weeds to those of the 

 coffee, and the females should be attracted in much larger 

 numbers by the presence of weeds than by the coffee 

 only; but from the roots of the former they would make 

 their way to those of the latter. But taking it for granted 

 that the plantations are kept perfectly clean, other mat- 

 ters have to be considered. In aualogous cases it has 

 been suggested that the earth from some distance round 

 the roots of the plants should be battered down by a 

 spade, and hardened, so as to render it difficult for the 

 female insect to deposit her eggs. This suggestion is not 

 without its importance, but the planters themselves must 

 consider its practicability in connection with the welfare 

 of the plants at the time the eggs are laid. Hardening 

 the surface might prevent the deposition of eggs ; it might 

 also cause the rain to run off instead of penetrating. 

 With regard to chemical remedies, (I am here consider- 

 ing only "grub,") I have little to suggest. According to 

 the reports submitted to me, several of the most approved 

 remedies of this nature have been tried with more or 

 less success. If any one in particular gives evidence of 

 more than usual success. I would advise that its use should 

 be continued. Saturating the earth round the plants 

 with dilute kerosine-oil should be tried. In France, the 

 use of bisulphide of carbou by "injection" into the soil 

 round the vines by instruments made specially for the 



