Vol. XVI. No, 398. 



THE AGRICULTURAL NEWS 



235 



BLOOD-SUCKING FLIES IN GRENADA. 



In the BMetni of Entumological Research, London, of 

 January 1917, Dr. A. MacDonald, who was in charge under 

 the International Health Commission of 'he campiign against 

 ankylostomiasis in Greuida, contributes some important 

 notes on blood-sucking flies in that island. Of the mosquitoes 

 in Grenada it appears tiiat the only Anopheline found 

 has been Anopheles argyrotarsis, K.I)., a recognized malaria 

 carrier, which has a permanent habitat in the shallow 

 moist flats in the neighbourhood of lagoons and estuarine 

 swamps round the island. Most of these are remote 

 from human habitations, and, as breeding places, should 

 be aboli.shed at little cost. The larva of this mosquito 

 prefer pools on which the sun will shine most of the day, 

 and may be found, tangled in algae, more frequently on 

 the shaded side of a sun-heated pool. They are also found 

 in temporary breeding plvces. such as wayside gutters, hoof- 

 marks, pig wallows, trenches, and flats in grass land through- 

 out the island in close proximity to human residences. 

 Stegomyi i fasciata, ¥., is common in and about the town of 

 St. George'.s, but is not so numerous in the country districts. 

 It was never found in empty cacao pods, the common breeding 

 place of Linuitus durhami, and only occasionally in rock holes 

 and once in a wild pine, associated with Wyeoiayia pertinens. 

 The lirvae are devoured by the larvae of Megarhinus in 

 captivity and therefore if Stegomyia eggs are laid in tree- 

 holes and wild pines frequented by Megarhinus, the larvae 

 will probably have little chance of reaching maturity. <:ule,r 

 fatigans i.s found in wayside pools and ditches, especially if 

 they are foul. Filariasis in an acute form is unknown in 

 Grenada. Several patients with morbid condition? diagnosed 

 as filariasis may have acijuired the infection elsewhere. 

 Lii:iatus durhinii, probably ihe most ubiquitous mosquito in 

 Grenada, occurs at elevations of 400 feet up to 2,300 feet. 

 Its larvae are found in old cacao pods, in fallen palm leaf 

 petiole?, and in the flower spathes of palms. The adult in 

 nature bites in the day-time. Ilaemagogus s/dendens, Will., 

 is well distributed throughout the wooded parts of the island, 

 e.xcept near the sea. One larva was obtained from a tree- 

 hole. The avocado or alligator pear (Persea gratissima) most 

 commonly provides holes in which mosquito larvae may be 

 found. Wyeomyia grenadenis, Edw., comes into houses after 

 dark, as does also W. partinens, Will., which breeds in tree- 

 holes and wild pines. Culsx similis, Theo., Deinocerites cancer, 

 Theo., Janlhinosoiiia posticata, Wied., and Ctilex infiictus, 

 Theo , were found in roadside gutters. The last named species 

 may be caught in houses after dark, and probably breeds in 

 tree-holes and wild pines. Janthinosom/x neoapicalis, Theo., 

 was found associated with Anoplieles argyrotirsis, as also 

 was Culer annulatuK. Stegomyia huscki, Coq., was found in a 

 collection of water in the petiole of a fallen palm leaf at an 

 elevation of 2,600 feet, and in a cacao pod at the upper 

 limits of cultivation. Larvae and pupae of an unidentified 

 Aedes, probably a new species, were collected from a tree- 

 hole and from a pine in a cacao plantation. The larvae of 

 Megarhinus haitiensis, D. and K., were; also found in wild 

 pines and tree holes, and fed readily on Stegomyia larvae in 

 captifity. Cule.r {Micraedes) conservator, D. and K., was 

 found with Corethrella appendiculata, Grab., in similar 

 breeding places, and a Culex allied to elevator, D. and K , 

 was bred from a wayside pool. The swamp mosquito of 

 Grenada is Ochlerotatus niger, Giles; it remains in deep shade 

 during bright sunshine, and emerges about an hour before 

 sunset, at which time it will bite as well a.s at night. 

 Deinocerites cancer, Theo.. also breeds in brackish water. 



The sandfly of Grenada which i.s' a species of Cerato- 

 pagon, is practically ubiquitous and causes considerable 

 annoyance, though no disease is known to be carried by it. 



Its control is difficult, as 16-mesh netting will not keep it 

 out. Of the blood-sucking flies which attack domestic 

 animals, Stomoxys is as common as in England, while 

 Tahanidae are uncommon, though a few unidentified speci- 

 mens were captiired, always in remote places. 



Virgin Islands of the United States.— In 



Th,; Board ot Trade Journal of April 26. 1917, appear 

 the principal sections of the Act of Congress dated March 3, 

 1917, 'to provide temporary government for the West 

 Indian islands acquired by the United States from Denmark 

 by the Convention entered into between the said countries on 

 August 4, 1916 and ratified by the .senate of the United 

 States on September 7, 1916, and for other purposes.' 

 Section 3 of the Act provides that on and after the passage 

 of the Act there shall be levied, collected and paid upon all 

 articles imported coming into the United States or its 

 possessions from the West Indian islands ceded to the 

 United States by Denmark, the rates of duty and internsJ- 

 revenue taxes that are required to be levied and paid upon 

 like articles imported from foreign countries. It is provided, 

 however, that all articles the growth or product of, or 

 manufactured in such Islands from materials the growth or 

 product of such Islands or of the United States, or of both, 

 or which do not contain foreign material to the value of 

 more than 20 per cent, of their total value upon which no 

 drawback of Custom duties has been allowed therein coming 

 into the United States from such Islands shall be admitted 

 free of duty By section 4, it is stated that until Congress 

 shall otherwise provide, all laws now imposing taxes 

 in these AVest Indian islands, including the custom 

 laws and regulations shall, in so far as compatible with 

 the changed sovereignty and not otherwise provided in tl^e 

 Act, continue in force and effect, except that articles 

 the growth, product or manufacture of the United 

 States shall be admitted there free of duty. It is provided, 

 however, that upon the exportation of sugar to any foreign 

 country, or the shipment thereof to the United States or 

 any of its possessions, there shall be levied, collected and paid 

 therron an export duty of $800 per ton (of 2,000 R.) 

 irrespective of polariscope test, in lieu of any export duty 

 that formerly was required by law. Under the United 

 States non-preferential tariff sugar of 96° pays $1-256 per 

 100 lb. and the St. Croix export duty is 40c. per 100 Db. 



Indian Runner Ducks.— It is admittedly une- 

 conomical to continue to breed and feed chickens for 

 table purposes under present conditions, and, as a matter 

 of fact, breeders in Great Britain have been officially 

 recommended to discontinue this branch of production 

 while feeding stuffs are in such short supply. It must there- 

 fore be obvious that arguments which apply to fowls are also 

 applicable to ducks, and, in view of the general recommen- 

 dation to concentrate on egg production, those who are favour- 

 ably situated for the purpose are advised by The Field of 

 May 26, 1917, to consider in this connexion the claims of 

 the Indian Runner. 



The Indian Runner duck is essentially a layer, and, in 

 consequence, is only of secondary consideration as a table bird. 

 As a layer, the Indian Runner is capable of such prolificness 

 that it has been described as a Leghorn among ducks. Its 

 great activity as a forager not only very materially reduces 

 the demands upon the food supply, but makes it extremely 

 useful in effecting a considerable reduction in insect pests, 

 while, probably owing to its distinctive foraging habits, the 

 eggs are of a much more delicate flavour than those of otlwj 

 breeds of ducks. 



