234 



THE AGRICQLTURAL NEWS. 



July 20, 1912. 



INSECT NOTES. 



A NEW PEST OF COWPEAS. 



In October 1911, oft'icers of the Imperial Department of 

 Agriculture discovered the larvae of a lepidopterous insect 

 causing a considerable amount of injury to cowpeas growing 

 in a field on an estate near Bridgetown, Barbados. 



The injury resulted from the attacks of these larvae on 

 the flower buds, leaf buds and young pods. From the con- 

 dition in the field at the time when this injury was first 

 noted, it seemed that the first attacks were on the buds, the 

 attacks on the pods only occurring at a much later time. 



The effect of a general attack on the buds would be to 

 produce a condition such as existed in this field, where the 

 plants though advanced in age had made very little growth 

 of vine, and as a result the surface of the field was not more 

 than half covered, although it would appear that the growth 

 of the vines should have completely covered the ground. 



As the cowpeas were grown principally for a green 

 dressing, it may be taken that the crop was not more than 

 50 per cent, of what it should have been, and probably this 

 condition was largely, if not entirely, attributable to this 

 insect. 



The loss caused by the injury to the pods is also severe, 

 for not only is the amount of the vine greatly reduced, thus 

 lessening the number of pods, but many of the pods which 

 are developed, are damaged to such an extent as to be practi- 

 cally worthless. 



On the occasion of one visit to the fields, the manager 

 seemed to attribute the condition to drought rather than to 

 insect attack. 



Specimens of the moth were reared from larvae and 

 sent to Dr. L. O. Howard, Chief of the Bureau of Ento- 

 mology, United States Department of Agriculture, Wash- 

 ington, through whose courtesy the insect has been studied 

 by Dr. H. G. Dyar, who will describe it as Ballovia 

 tistipennis, creating a new genus, and a new species. 



The full-grown larva of this species measures about 

 3^-inch in length, and is of a pea-green colour until it is just 

 about to enter the ground to pupate. The pupal stage extends 

 over a period of fourteen to seventeen days. 



The moth measures about !;-inch across the outspread 

 wings, and aViout Ainch in length when the wings are closed. 



The general colour of the forewings is a pale grey above, 

 and a silvery grey below, while that of the hind wings is 

 a translucent white with pale honey -yellow veins. A striking 

 characteristic is a large dark spot in the basal half of the 

 I'orewing. 



This insect is capable of becoming a serious pest and it 

 may easily be realized that methods for its control can only 

 be devised by experiment. 



An insect causing similar injury to the horse bean 

 {Canavalia ensiformis) occurs in St. Kitts, but up to the pre- 

 «tnt time the adult has not been obtained. 



THE CANE FLY IN MARTINIQUE. 



The Jtulletiii of tlie Bureau of Aaricultural Inttlltijence 

 aiid of Plant Diseases for April 1912 (3rd year, Ko. 4) 

 reviews at page 1074 a paper entitled La Maladie de la Canne 

 a Sucre a la Martinique, by Eugene Bas.<ie-res, which was 

 published in Surrerie Indiqcne et C'oloniah, Paris, January 9, 

 1912. 



It appears from the review that, at the end of 1910, 

 37 acres of cane .vere observed to be .^uttering from attacks 

 of an insect not previously known there. This proved to be 

 Belpha.f mrc/tarii'ora, Westwood, the cane fly which appears 

 occasionally in Barbados and other islands. 



The author considers the development of the fly in 

 Martinique to be favoured by three causes: the carelessness 

 of the cultivators, who neglected the control of the pest on 

 its first appearance; the custom of using large quantities of 

 mineral fertilizers and scarcely ever employing farmyard 

 manure: and finally, the almost complete absence of insecti- 

 vorous birds in the sugar-cane plantations. 



M. Bassieres advises the following method of control: — 



(1) When the large or small canes are badly attacked 

 it is necessary, as far as possible, to burn the infected zones. 

 The canes could then be sent to the mill without further 

 trouble. 



(2) In the case of tall canes, which have sutt'ered less? 

 severely and can thus, without much loss, be allowed to 

 grow till the usual time of harvest, it is sufficient to cut 

 them as soon as possible after burning. 



In the meantime, and in inaccessible places, a partial 

 burning will be advisable, and also the collection of the eggs 

 of the insect, etc. 



(3) Young canes, intended to be cut in 1913, and which 

 are, so far, not irremediably affected, should be treated with 

 an insecticide. 



For this purpose, the writer recommends various emul- 

 sions: with petroleum and soap bases according to the 

 American station and Hubbard-Eiley formulae; with a basis- 

 of petroleum and hot milk of lime; bases of soft soap, tobacco 

 juice, sodium carbonate and alcohol; of soft soap and 

 spirits of turpentine; of soft soap and commercial ammonia 



The preparations of petroleum and of ammonia seem to 

 be the most efficacious against the majority of the insects 

 belonging to the same family as Delphax. 



The Brown Hard-back. — The occurrence of the 

 brown hard-back {Phytahis siuitlii, Arrow.) in Barbados and 

 Mauritius, was mentioned in the Insect Notes in the A^ri' 

 cultural Neu's of March 16 last (see Vol. XI, p. 90). 



In a letter to the Imperial Commissioner of Agriculture, 

 under date of July 5, 1912, the Superintendent of the Local 

 Department of Agriculture, Barbados, announces that the 

 Assistant Superintendent has discovered that the larva of 

 Phi/talus smithi is parasitized by a black wasp, which has 

 been identified through the courtesy of Mr. Guy A. K. 

 Marshall, Scientific Secretary of the Entomological Kesearch 

 Committee, as Tiplda parallela, Smith. 



The information is of considerable interest, and if it can 

 be shown that Tiplda parallela is largely responsible for the 

 fact that Phytalus smithi occurs in only small numbers in 

 Barbados, is likely to prove of the greatest benefit in those 

 places where, as in Mauritius, the brown hard-back is abun- 

 dant and its larvae are serious pests as grubs in the soil, 

 attacking the roots of sugar-cane and other crops. 



