October i, 1884.] 



THE TROPICAL AGRICULTURIST. 



257 



THE COCKCHAFER-BEETLE GRUBS AND 

 THEIR DEVASTATIONS. 

 Tt seems a great pity, that, with Mr. McLachlan's 

 opinions on questions referred to him in regard to 

 grubs and their ravages on Ceylon coffee estates, the 

 documents submitted to him, especially the numbered 

 points, I., II., III., &c, to which his attention was 

 directed, were not published simultaneously. In the 

 absence of Mr. Christie's report and the details given 

 by Mr. Braino and others, a degree of obscurity 

 surrounds some of the details ; but what is clear is, 

 that, however much light naturalists may throw on 

 the life history of the insects (and their name seems 

 to be "Legion," because they are many), which de- 

 vour the feeding rootlets of grass, bnshes and trees, 

 men of science are as helpless as the most ordinary 

 planter or farmer in providing an effectual remedy. 

 In this respect, the history of black or brown bug 

 which closed the pores and sucked the juices of the 

 coffee tree; tho black or brown grub which "ringed' 

 and destroyed millions of young coffee plants in the 

 field; of the white or yellow- white grub which de- 

 vours the feeding rootlets of the grown coffee bushes ; 

 and, finally, of the fungus (worst pest of all) which 

 saps the very life of the plant by exhausting the 

 juices of its foliage — is uniformly the same. There 

 are means, no doubt, which on a limited scale have 

 been found effectual for the destruction of each of 

 the pests named, but it is the vast profusion of the 

 insects or fungi and their almost universal diffusion 

 (bug and grub coming and going, but the fungus being 

 chronic,) which render the application of remedies 

 impracticable. There is a very valuable American 

 work on insects injurious to vegetation, in which a 

 large amount of information regarding the Melolonthidcc 

 or "May bugs" is collected, and one of the 

 statements made is that in view of the oc- 

 casional terrible destructiveness of the cockchafers, 

 " the Society of Aits in Loudon, during many 

 years, held forth a premium, for the best account 

 of this insect, and the means of checking its ravages, 

 hut without having produced one successful claimant." 

 This does not look encouraging, and it is simply 

 tantalizing, in view of the almost entire absence of 

 insectivorous birds from the coffee estates of Ceylon, 

 to be advised to encourage rooks (the very crows 

 of Ceylon give the grubs in coffee a wide berth), 

 gulls, jays, shrikes, &c. It is of no practical use to 

 us to be told how the rooks and gulls follow the 

 ploujh at home and gorge themselves with the up- 

 turned grubs. From the fact that our cultivated 

 plant is perennial and from the steep features of most 

 ooffee estates, ploughing iu coffee estates is impossible. 

 Pigs, if peuned over successive portions of a coffee 

 field, would soon rout out the grubs, but we sup- 

 pose the reason why this remedy has not been fried, 

 has been the certain conviction that in routing out 

 the grubs the porcine diggers would root out the 

 coffee bushes. If we could procure pigs "learned" 

 enough to make and observe the distinction, the pig 

 rtmedy would be a red one. We suppose the very 

 promising remedy of compelling the grubs to come 

 to the surface by spreading gunny bags or other 

 coverings over the ground was found too expensive ? 

 Careful forking of the soil (our substitute for 

 ploughing), if carefully conducted and so as not to add 

 to the destruction of the tender rootlets, was no doubt 

 one oE the best possible modes of up-turning the grubs 

 from their subterannean abodes and destroying them, 

 while the soil received culture which opened it to 

 33 



the genial influences of sun and air and rai But 

 this very process, no doubt, facilitated the deposit of 

 fresh stocks of eggs by the females of the cock- 

 chafer beetles, The remedy apparently suggested by 

 some planters of beating the ground into such a state 

 of hardness that the beetle could not penetrate it, 

 would be an injurious, if not a fatal expedient, and as 

 for the advocates of weeds on estates and those who 

 hold that gruhs do not attack healthy roots of healthy 

 plants, the accumulated evidence places them entirely 

 out of court. It is unhappily too true that as in 

 ringing young coffee plants the brown grub chose 

 the plants of most luxuriant growth, so the big, white 

 grub of "the patana cockchafer " prefers the healthiest 

 and most succulent rootlets, whether of grass or trees, for 

 his food. We must, in many cases, go beyond our own 

 limited experience. Judging from what we have seen 

 in Ceylon, we should lay down the proposition that 

 white ants never attack living and healthy tissues. 

 But it is beyond dispute that in India, the ten planters 

 have to remove dead timber from their land, lest the 

 white ants from the decaying wood should attack 

 and destroy their tea plants. We have not heard of 

 white ants attacking tea in Ceylon, and happily, grubs, 

 except in rare and isolated cases, do not seem to 

 affect the tea plant. While cinchonas planted on 

 patanas were savagely attacked by grubs, tea plants 

 put out in like condition were left scatheleps. This 

 is a very important fact as regards our new enter- 

 prize. It is curious that, as stated by Mr. Christie, 

 that in the Maskeliya district the damage done by 

 grub should first have attracted attention in 1877, the 

 year of culminating prosperity for coffee aud every 

 other interest in Ceylon. In that year, however, 

 Jlemilcia vastatrlr had been at work for eleven years, 

 and in the older districts grub and the damage in- 

 dicted by it had been too well known many years 

 previously to 1S77. Maskeliya seems, however, to 

 have a chafer (appropriate name) of its own. 

 Mr. Christie reported that trees reduced to living 

 skeletons by the ravages of grub, were particularly 

 liable to the attacks of leaf-disease. There can be no 

 doubt, on the other hand, that the debility induced by 

 continued attacks of leaf-disease rendered the. trees 

 less able to resist or recover from the attacks of grubs. 

 Unhappily evils of this kind act and react on each 

 other, as primary and secondary diseases do on the 

 human frame. We are surprised to find Dr. King 

 quoted as saying that the grubs, which a couple of 

 years ago devastated the Darjiling Botanic Garden, 

 were the larva? of an unknown beetle. There can 

 be no doubt, we should think, they were cockchafer 

 grubs. We, in Ceylon have not got the marked cold 

 and hot seasons which Dr. King refers to as regulating 

 the downward and upward movements of the grubs, 

 but of course, here as elsewhere, there are seasons 

 when the grubs come close to the surface and, when 

 they can best be dealt with. In Europe the grub 

 after existing for three years in the soil in the larva 

 state, changes into a beetle, but the now winged 

 insect is in no hurry about its resurrection, but 

 remains in a semi-dormant state near the surface 

 for the fourth year. This is the stage at which 

 specially the beetles should, if possible, be dis- 

 posed of, But Mr. Haldane is inclined to think 

 tbat the influence of our tropical climate shortens the 

 subterannean stages of the life of the insect, and the 

 decision of this question Mr. McLachlan relegates to 

 observers in Ceylon. It is quite evident from the 

 number of the Ceylon specimens sent being declared 

 new, unknown or doubtful, that a wide field for in- 

 vestigation is open to entomologists in Ceylon We 

 hope Mr. Christie's report and Mr. Braine's note, if 

 not already published (2), will be given to tho world. 

 Our wealth (?) in beetle life seems perfectly marvellous. 

 We should like specially to receive information as to 



