lOG 



THE AGRICULTURAL NEWS. 



April 3, 1909: 



INSECT NOTES. 



A Parasite of the Cotton Worm. 



The letter which is published lieicuith from 

 Mrs. Patterson, of St. Vincent, is ;i response to a recent 

 article in the Agriiulfuntl Xncs. The specimen 

 referred to in the letter has proved to be the same as 

 that discussed in tiie article mentioned. 



It would be very useful if other readers woidd 

 make careful observations on tlie habits of insect pests 

 and their natural enemies, and communicate their 

 observations to the Head' Ottice of the Imperial 

 Department of Agri'julture. The tullowing is Mrs. Pat- 

 terson's letter : — 



The article ' Some Parasites of the Cotton Worm " on 

 |Mge 74 of Vol. VIII, No. 179, of the Agricaltural Xews, 

 reminds me that in the season 1906 some parasites were 

 hatched here, which, from the specimen sent, yon will see 

 were Chalcis orata, Say. 



As far as my observation went, the method of attack 

 was somewhat ditl'erent from that de.scribed by Mr. Jenunett. 

 C!ertiiin larvae of the cotton ' worm ' at the end of the larval 

 period were seen to be of a red purple colour, and it was 

 these which after ])upatint; yielded the C/in/ris imago. 

 I hope to verify this during the coming season. 



Millions and Malaria. 



The followinjj; notes which have been communica- 

 ted by Dr. C. W. Branch, M.B., C M , of St. Vincent, may 

 l>e of interest to the readers of the Ar/riculfaral A^cics. 



l)r. Branch refers to the theory which has been 

 advanced that the millions, on account of their habit of 

 feeding on mosipiito larvae, are wholly responsible for 

 the alvsenco of the malarial mosquito from Barbados. 



It will be seen by reference to the Agricultural 

 News, Vol IV, pp. 127 and 138, that this theory was 

 strongly advocated b}- a correspondent in 1904-5. As 

 a icsult, considerable interest has since been e.Kcited 

 ill connexion with the part played by millions as the 

 natural enemies of mosejuitos. 



This Department was called iipon for inforniation 

 with regard to the habits of millions, and the possibility 

 of transporting them to other colonies and othei- conn- 

 fries, and the booklet referred to by Dr. Branch 

 (Pamphlet Series, No. 5.5, Impeiial Department of 

 Agriculture) was j)repared in answer to this demand 

 for information, and not in support of any iheor}'. The 

 statement is made that millions arc very efficient, 

 natural enemies of mosquitos, and that they will 

 probably be found iisefid in reducing the numbers of 

 mosquitos wherever they can be established. 



The Deiiirtment of Agricultnro has l.iteiy issued 

 a booklet on ' .Millions ;ind Mosquitos,' which seems to have 

 Jiad its origin in ti\i.> suggestiou that the 'millions' arc to 



be credited with the absence of anepheliuc mosquitos, and- 

 consequently of malaria, from Barbados. 



This idea has perhaps been somewhat hastilj- accepted 

 without full consideration of the bionomics of the animals- 

 concerned, and a dangerous sens(! of security may be 

 engendered. ' Let him that thinketh he stnndetli take heed 

 lest he fall.' Notwitlistaudiiig free inunigration, Mauritius was. 

 free of malaria till the year 1860, when the population was 

 afflicted with ;in epidemic which, it has been estimated,, 

 killec' one-tifth of the ))opulation. It is presumed that 

 anoplielines nui-st have been introduced just before that year; 



Millions undoubtedly devour all mosquito larvae 

 (anoplielines included) that they can get, and are therefore 

 useful for stocking all permanent collections of water which 

 caimot be screened — ponds, artificial basin.s, uncovered 

 reservoirs, etc. In Barbados such waters will breed C'ide.r 

 /ati;/anx, which in spite of millions is too common, and does 

 considerable harm as an intermediate host for Filnria 

 /lancriiffi, the parasite of ' fever-and-ague ' and ' Barbados 

 leg.' St("i(imyia fanciatn will not usually breed in such 

 large collections of 'water, but, as is recognized, prefers 

 bottles, tins, and holes in rocks and trees. 



The malaria bearer of these part.s, Ci'llin [.Vnopheles] 

 /(n///riitiir.-<is, Vireeds in small puddles of dirtj- water with 

 green algae, such for instance as occur on the margins of 

 streams in dry weather, in the beds of occasional water- 

 courses, and in swampy ground ; in fact, in places where 

 millions do not naluially occur, and in which they cannot 

 conveniently be put. Mr. AV. Patterson of the Agricultural 

 Department in this i.sland [St. Vincent], has actually found 

 C cilia in a puddle 4 inches wide and 2 inches dee|). 



In countries where the malaria bearers breed in suitable 

 water, millions no doubt will limit the prevalence of malaria, 

 but they will not do .so in the West Indies. 



The absence of Celli'i from Barbados nuist be ascribed 

 to some other cause • than the millions. Po.ssiblj- some 

 voracious aipiatic insect is particularly abundant in the 

 puddles which suit Cellin. But it must be feared that such 

 alone cannot absolutely e.xterniinate a species of mosquito. 



The truth no doubt lies in the o.scillations of the 

 Antillean continent. Barbados on the coastal plateau has 

 been often conqjletely submerged and only slowly regains 

 a faiuia. By luck, the Ccllia lias not been introduced since 

 the last suliiiieigence. The fauna and tlora of Barbados are 

 limited in comparison with those of the neighbouring lofty 

 i.slands which have never been completely submerged. 



It is ' u|i to ' the Barbadians to see that Ccllin is not 

 accidentally introduced by means of imported ca.ses of plants. 

 'I'he fumigation deman<lcil bj- the Department of Agriculture 

 is their ijiolectioii. 



DEPARTMENT NE'WS. 



'i'he Imperial Coniniissioner o( Agriculture returned 



to Barbados from St. Lucia on .Man 



ast, bv the 



K.M.S. 'Esk.' Mr. Ballou also returned from Montserrat 

 bv the same vessel. 



The Commissioner left Barbados on March oO, b}' 

 the R.M.S. ' ICdcn.' for a visit to Dominica. He will 

 leave the latter island on April 5, and proceed to- 

 Antigua by the C.L.S. 'Ocamo.' Dr. Watts is not;- 

 e.xpected to return to the Head Oltice until April '20. 



