234 



THE AGEICULTUllAL NEWS. 



July 16, 1904. 



INSECT NOTES. 



Grenada. 



The followiiiE; :iie f urtlier extracts from Mr. Ballou's 

 rejiort on his recent visit to CJrenada. The subject 

 dealt ^vith is the 'black blight ' which is so prevalent 

 in that island. Further information on this pest ■will 

 be found in the Ayrlcidtural Xeics, Vol. II, p. .37: — 



Black blight i.s a fungus of the genus Ca^modium. It 

 fintls nutriment and favourable conditions for growth in the 

 secretions of the scale insects and is nearly always to be seen 

 in greater or less quantity on scale-infested trees. As a first 

 cau>e of injury, it is couiparativel_v insignificant, the damage 

 done to plants attacked by black blight being almost 

 entirely damage b}' scale insects. 



Several trees are always to be seen which show the black 

 blight on leaves and twigs. The most striking of these are: 

 clammy cherry (CorcUa Collococca), mango {Mungifcra 

 indica), breadfruit (Artocaijnis incim), sai)odilla (Sapota 

 Achras), guava (I'sidimu 'jiiavu), lime {Citttis medica, var. 

 acida), orange (Citnif: Aurantiitin). 



Black blight al.--o seems able to subsist on the products 

 of several ditt'erent kinds of scale insects, prominent 

 among which are the following : all the species of the 

 shield scales (Lerrmium), the glassy star scale (Vinsonia 

 ateUifern), the mussel scale {Mytila$2i's citricohi), and 

 the mealy shield scale {I'mfopulviiiaria 'p!/r{formis). !Many 

 of the plants afl'ected by these scales, and the attendant 

 black blight, live on j^ear after year, though the upper 

 surfaces of all leaves seem to be thickly coated with the 

 mycelium of Capnodimn, and the under surfaces and small 

 twigs seriously attacked by scale insects. 



No serious attack of black blight, or the scale insects 

 causing it, has yet been observed on cacao or nutmeg, and 

 it may be stated as a general truth that, 

 insects attack these plants, the black 

 and that any observant planter will be 

 the beginnings of such attack, and by 

 of contact insecticides will be able to ward off the attack 

 before it assumes serious proiiortitms. The fact that for so 

 many years cacao has lieen grown in these islands, where 

 manj" of these scale insects are native, and has never been 

 seriously attacked by them would lead to the supposition 

 that it is not a favourite ffiod plant for the scales. 



Mr. ilacXeill, formerly Agricultural Instructor at 

 Grenada, in a letter dated November 1902, gives a long 

 list of plants affected by l>lack blight and says : ' ^^"hen 

 maugo.s, breadfruit and other trees become atlected with 

 the blight, the crops suffer and I have heard of cases 

 where the trees died:' but he does not say from his 

 own knowledge that lilack blight does kill trees, or that 

 he has ever seen trees that he considered had been killed 

 Iiy this pest. As Ijearing on this point, I would refer 

 to the mango. This tree, in many places, is affected year 

 after year by black blight, and yet each new crop of leaves 

 comes on and fully reco\ers the tree so that with the casting 

 of the old leaves and the bursting of the new, the tree stands 

 to all appearances a clean and healthy tree. Manj- affected 



until the scale 

 light will not, 

 able to detect 

 the application 



leaves are left, however, and in a short time the scale insects 

 take possession of the new growth and the black fungus soon 

 appears on the leaves which were clean. 



When in Grenada, I noticed that the trees in the 

 \iciuity of St. Georges were nuicli more commonly attacked 

 Iiy black blight than trees along the leeward coast and in the 

 northern part of the island. What conditions are responsiblt 

 for this I am not able to say, but I presume that the more 

 unnatural nature of the locality leads to this prevalence. 



The extermination of black blight in an island like 

 Grenada wouhl be a practical imiiossiliility. That is to say, 

 the expense of exterminating the various scale insects which 

 furnish conditions favourable to the growth of the black 

 l)light would entail an enormous exjienditure of money, which 

 would hardly be warranted until the pest ga\e evidence of 

 being seriously injurious to a valuable crop, and it would 

 necessitate the destruction of so manj- trees and food plants 

 of the scale insects that the results might be more 

 unfa\-ourable and far-reaching than would be supposed. The 

 contiol, however, of black blight, and of the .scale in.sects it 

 follows, is, on the whole, a simiile matter on any given area. 



In conclusion, I would again point out that black blight 

 is unsightly but comparatively uninjurious ; the scale insects 

 which it follows may, however, become a serious pest, but 

 they can be controlled. 



Entomology in Hawaii. 



The Hawaiian Government emjiloys four entomologists 

 who are officers of the Board of Commissioners of Agriculture 

 and Forestry. The chief entomological work is given in the 

 Hawaiian Forester and Afjrlculturist (Vol. I, no. 4, April 

 1904) as coming under two heads : (I) supi>ression of insect 

 [lests already in the islands, and (i') prevention of the 

 introduction of new insect pests into the islands. 



For the former the natural enemies of the various 

 insect pests are depended upon to a large extent. Two of 

 the four entomologists .spend a large part of their time 

 travelling in search of natural enemies in the places from 

 which different jiests have been imported. 



The work under the second head is done by the resident 

 entomologists, who inspect all im}>ortations of plants and 

 decide whether they shall be allowed to land, and, if so, 

 whether they shall be treated in order to deal with any 

 insects that may have been found on or among them. 



In addition, the matter of spraying and the best 

 cultural methods for deiiling with pests attacking the various 

 crops receive a good deal of attention. 



At present the leaf-hojiper of the sugar-cane is one of 

 the most troublesome pests. Not only does it injure the 

 canes by puncturing the leaves and stems in feeding, and in 

 egg-laying, but in addition these i>unctures serve to give 

 entrance to fungoid diseases. 



The leaf-hopjier of the Hawaiian Islands {Perkinsiella 

 saccharicida) is closely related to the cane fly (Delp/ut.c 

 sacefiai-iiwa) and the corn fly (Delpha.r niaidis) of the West 

 Indies, but it is much more serious a pest than the latter. 

 (See Af/ricidtimd A^'ews, Vol. Ill, p. 154.) 



Pickling Lemon and Orange Peel. 'The 



fruit i^ cut in half and the lailji extracted. The peel is 

 then thrown into open casks of salt and water and .soaked 

 for three days. The water is then drawn off and the peels 

 are packed in layers in barrels. When the barrel is full, it 

 is closed down and salt water is poured in through the bung 

 to fill up completely. When the fruit is saturated the cask 

 is sealed.' ( West fndian Bulletin, Vol. V, p. 70.) 



