42 



THE AGRICULTURAL NEWS. 



February 3, 1906. 



INSECT NOTES. 



Scale Insects attacked by Fungi. 



The Curator of the Botanic Station at Dominica 

 recently forwarded to the Imperial Commissioner of Agri- 

 culture some scale-infested twigs of lime trees from an estate 

 in that island. 



Eroni the correspondence accompanying the .specimens 

 it appears that a greyish fungoid growth on the lime plants 

 is supposed to have caused the death of a number of the 

 plants. 



Examination of the specimens sliows that the fungus 

 referred to occurs only in connexion with the orange mussel 

 scale {^fi/filaspis cifricola), and is probably parasitic on the 

 scale insects, and not on the lime trees. The cause of the 

 death of the plants, then, would not be the fungus, but the 

 .scale insects, or some other cause which has been overlooked. 



In the Agricultural Nevs (Vol. II, p. 232) reference is 

 made to two kinds of fungi found in Dominica on .scale 

 insects. One of these is probably the same as the one under 

 discussion, although it has not been identified. The other 

 is reddish in colour and has been identified as Sphaeroitilbe 

 voccojihtla. 



The estate on which these plants were growing is 

 situated at an altitude of about 1,000 feet, in a district where 

 the rainfall is about 200 inches per annum. The land has 

 been recently cleared and there is a large amount of decaying 

 vegetable matter on the surface or in the soil. The lime 

 plants are young, and it is likely that these conditions and 

 the scale insects present are together responsible for the 

 death of a few trees, while the fungus is present as an enemy 

 to the scales and not injurious to the plants. 



cost of the materials added, which is very small. Samples 

 treated in this manner were sent out to India by the above 

 syndicate, whose offices are in Temple Bar House, E.C., and 

 satisfactory reports regarding the same have recently been 

 received. The applicxtion of this treatment will now 

 permit of the more e.xtended use of wood in tropical couutrie.* 

 for all puri)0ses, and may lead, in many cases, to the 

 substitution of ordinary timber for more exiiensive hardwoods. 



The Protection of Wood against White Ants. 



The following note appears in the Gardeners' 

 Cliroi)iclc for January 6: — 



All timbers in tropical districts, with the exception of 

 a few of the more expensive kinds, are subject to the 

 depredations of white ant.s, whilst, so far, no treatment for 

 the protection of wood against these pests has been 

 commercially .successful. Creosote and other ,niineral oils 

 have been tried, but they are not lasting. ; They only 

 partially imiiregnate the wood, and cannot be used for indoor 

 work. Various chemicals have also been employed, but in 

 general these are inetticient, or too costl}-. The method 

 introduced, however, by the Powell Wood Process Syndicate, 

 to which we alluded some time since, appears to overcome 

 these objections. This process consists in first boiling the 

 wood in a .saccharine solution which exi)els the air. In the 

 subsequent cooling, the solution is ab.sorbed by the tissues 

 with the result that the wood is strengthened and improved 

 in quality. It is afterwards artificially dried, and the ordinary 

 process is then complete, the wood being thoroughly seasoned. 

 In order to render wood proof against the attacks of white 

 ants, it is only necessary to combine with the saccharine 

 •solution certain .substances obnoxious to these insects, which 

 substances are absorbed by the wood along with the saccharine 

 solution. The extra expense is thus confined to the bare 



Scale Insects on Cotton. 



The subject of ratooning cotton has been discussed at 

 some length in the publications of the Imperial Department 

 of Agriculture, and reasons have been given why the practice 

 is undesiral.ile. This was especially dealt with from an 

 entomological point of view in an article in the A<jrirultural 

 Neirs (Vol. IV, p. 262). The following instance is an exainple 

 of the bad effect of keeping old and scale-infested plants up to 

 and after the time of planting for the new crop. 



On one estate in Barbados a field of cotton was kept 

 over from the previous season until after planting had been 

 done for the new crop (July 1905). Directly to leeward and 

 adjoining this field, several acres of cotton were planted, while 

 almost adjoining this and across the wind from it another 

 new cotton field was establfshed. The old cotton was 

 allowed to remain until the young plants had been growing 

 some time, even though it was known to be badly infested 

 with the white .scale {Chionaqiis minor), and the black scale 

 {Lecanium niijruiit,}. 



Itecentl}-, these two cotton fields have become very 

 seriously infested with the black .scale. In one of them it has 

 been neces.sary to pull up and burn all the plants, in the 

 other the yield of cotton will be very small. It may be 

 stated that the red maggot occurred in both these fields, but, 

 at the time the plants were being pulled up and burned, the 

 scale insects were doing the greater damage. 



The injury to these cotton fields from scale insects may 

 be attributed, almo.st entirely, to the presence of the old and 

 infested cotton near the young plants. 



DISPOSAL OF CACAO HUSKS. 



On several occasioriS attention ha.s been drawn in 

 the Agricultural Neu's to the desirability of burying- 

 cacao husks. This method of treatment is particularly 

 referred to in the last volume (pp. 203 and 239), where 

 it is advocated as necessary to prevent tJie spread of 

 I_)od-rot and other diseases. It is very important that 

 this practice should become general all over the 

 West Indies. 



In a recent report to the Imperial Commissioner 

 of Agriculture, Mr. George Branch, Agricultural 

 Instructor in Grenada, mentions that, at all the places 

 visited by liim, he is recommending that cacao husks 

 should be buried as soon as possible after the removal 

 of the beans. 



A special aspect of this question is brought ui> 

 by Mr. Branch in the following words : — ■ 



Not only is it an important matter from an agricultural 

 jioint of view, but in districts where the peasant holdings 

 are small and the houses close together the matter becomes 

 a sanitary one. The cacao trees are sometimes growing so 

 close to the houses that the branches actually touch the 

 buildings, and the shells collect water, which, after a while, 

 not only possesses an obnoxious smell but also contains- 

 abundant larvae of mosquitos. 



