94 



THE TROPICAL AGRICULTURIST, 



[August i, 1885, 



the following average result, viz. :— 



Per day. 

 Cock Robin 92 trips a day \ ^glS tripa. 

 Mother Robin 121 „ ,. J 



Take the average to be two larv.-e at 

 each trip (a low estimate) ; then 

 larva' = double the number of trips or= 426 larvas. 

 As the cage on this occasion contained two young 

 ones, the allowance for each bird was 213 larvre. 



Now, even say the adults will not require more larvas 

 than the number they give their young, viz. 213 each, 

 we arrive at 852 larvffi per day, for the four birds, or 

 35,784 for the six weeks the young were in confinement. 

 Again, at and in the neighbourhood of the nursery 

 grounds and garden, we have at least five families of 

 say six each, including the adult birds, i.e. 30 birds, 

 each capturing 213 larvjs daily : then for the year 

 of 365 days we arrive at the enormous number of 

 2,332,350 destructive larvse captured by the five 

 families of robins. 



In this calculation, you will see, we have not allowed 

 more food for the adult birds, than was sufficient for 

 the young in confinement, and we think J more might, 

 with safety, be added to the number of larvfe de- 

 stroyed. It is better, however, to be on the safe side, 

 and these figures as they stand, are sufficiently startling. 

 VVe have not yet got any data to give you, as 

 to the destruction of larvae by the " Warblers," 

 [Syhiadce) and "Bush-creepers" {Leiotrichincii), and 

 other small fry ; but we are positive that these are 

 more useful to us than the " Eobins " {Saxieoliiiie), 

 the " Bulbuls " (Pycnonotinte) and even the "Fly- 

 cdXo'wera" (Musckapina'), Little " Snips," the " Tailor 

 Bird" (0. longkauila) warbler, has an insatiable 

 appe tite and is activity personified, or we should per- 

 haps say ornithofi/il (to coin a word). 



These smaller insect-feeders are the very birds our 

 cacao planters should show the utmost attention 

 to, and encourage in every way. VVhy, little Snips 

 and his nimble confreres are a match for Helopeltia 

 any day, if you can only get them to locate and 

 pay their addresses to that vile little pest. We'll back 

 a dozen tailor-birds or other warblers against the 

 entire cooly population of the estate, at Helopeltia 

 catching. The plan would be to plant up any waste 

 patches or swampy ravines between the cacao fields 

 or even the road-sides, with thick clumps or belts 

 of wild cane, or ether sort of tall reed, in which they 

 delight, and where they would soon make their home. 

 These of themselves would form a sort of shelter for 

 the cacao, and, as they do not throw down seed, 

 would do no mischief, if the roots were kept from 

 trespassing by means of trenches. 



To all lovers of horticulture, I would respectfully 

 say, try and rear your robins regularly, and other 

 species of insectivorous birds if you can, and attach 

 them to your gardens and compound. We all know 

 how trying it is to one's equaniuiity of a morning, 

 to discover that that grand Idoom of Gnpt. Chriity, 

 La France, or Qloire Duchess rose, which we were 

 looking forward to feast our eyes on, has been half- 

 deviiured during the night by a wretched larva of 

 one of the G'comitricttv moths. 



Watch over and foater your robins, and no such 

 catastrophes will occur. 



. WH YT E, Naturalist and Florist. 

 P. S. — On the question, as to how Helopeltia can 

 be k' pt iu subjection, I feel more and more con- 

 vinced that it can be vanquished by the steady and 

 peraeveriug introduction and application of its natural 

 euemie~. Wo have no mysterious and insidious fungus 

 to deal with here ; nature has provided the cure, if we 

 can only apply it. I mcutioucd in my last letter, 

 that I thought (and iu f .ot 1 feel sure) that lizards 

 would be moat destructive, and I now tea that some 

 plantcra are introducing red ants, a cajjital move I 



think. They are the veritable tigers of the insect 

 world, and cannot fail to be most beneficial. Hunt- 

 ing down such small insects with coolies seema aa 

 expensive, clumsy and slow operation. I believe 

 thoroughly in the smaller insect-feeding birds, as th9 

 most elficacious cure. No coast advances, no check- 

 roll or montiily pay required for them. We could 

 not even purchase their services : they are given with- 

 out money and without price ; are in fact, in a two- 

 fold tense of the word, priceless. 



INVESTIGATION OF COFFEE LEAF-DISEASE: AN 



APPARENT REMEDY BY AN UVA PLANTER. 



Sir, — I have never seen the report made by Mr. 

 Marshall Ward regarding the result of his investig- 

 ations into the nature of our coffee leaf-disease nor 

 the report of anyone else, and I am altogether ignor- 

 ant as to the conclusions which have been come to 

 in the matter. My own observations and investig- 

 ations, which have extended over a period of nearly 

 nine months, have therefore been entirely independ- 

 ent of the opinions of others. Like a great many 

 other planters, I believe I have hitherto been led 

 to regard the pest as a parasitical fuiujus, and even 

 now I am not prepared to deny that the saffron- 

 coloured spots which appear on the underside of 

 coffee leaves are a fungus, but, if it Ib, it appears to 

 me to be one which derives its nourishment from 

 the air and not from the substance or juices of the 

 leaf. I have never yet seen a leaf change its healthy, 

 looking aspect until the development of the insect 

 which is inseparably connected with the so-called 

 fungus, I have therefore been led to the con- 

 clusion, after long and patient investigation, that the 

 evil effects are due to this insect and not to the 

 fungus, if it be a fungus. That the maggot or Zwtia 

 is produced from zoospores there can be no doubt. 

 The question therefore comes to be : What relation do 

 living zoospores or germ cells, ova or spawn bear 

 to the fpores of the supposed fungus ? For the one 

 does not exist without the other, and it is only 

 after the maggot is developed that the leaves change 

 their color, blacken and die. This creature, although 

 it is very minute, is not so mioroscopio that when 

 it is full-grown it cannot be perceived by the unaided 

 eye, for it is then about the sixteenth of an inch 

 in length, and it is surprizing to me that I have 

 heard nothing of it befoie. My microscope is un- 

 fortunately not a very powerful one, so that probably 

 several hours must elapse before the newly-hatched 

 larva becomes recognizable within the range of my 

 optics. It is then a mere speck, like a molecule, 

 of shining silver. Within 36 hours however it is a 

 perfectly-formed maggot, of a red blood color, cylin- 

 dric^il in form, no feet, body consisting of ten seg- 

 ments counting the head and tail two, which are 

 both white ; back and abdomen red blood colour with 

 two white longitudinal lines along the undersides. 

 The periphery of the segment rings are also tipped 

 with white on the lower sides. But the head is 

 armed with a most formidable, horny-looking pro- 

 boscis, long enough to pierce the tcarf skin of the leaf 

 and penetrate the pulp. For three days after it 

 makes its appearance it does not move much from 

 its original position but appears to feed upon the 

 yellow-coloured rtsiclea which were previously broken 

 up by the female insect and now assume a moist, 

 semi-iluid appearance, adhering together in masses. 

 About the fourth day of its existmce it begins to 

 show active signs of life, moving freely amongst the 

 accumulated masses of jfovilla, and in nine or ten 

 days' time it has attained its full eize, being, as I 

 have said, about the sixtetnth of an inch in length, 

 and is then quite perceptible to the naked eye. 

 It now quits its native spot in search of " frejh 



