Vol. VIll. Xo. 193. 



THE AGIIICULTUKAL NEWS. 



299 



THE PARASITIC FUNGI OF SCALE 



INSh;CTS IN THE WEST INDIES. 



The following is ;i short acuonnE of the f)ar;isitic 

 fungi which have been found on scale insects in the 

 We.st Indies up to the present time. The jjresenoe of 

 some of these forms has been reco,2;nized for several 

 vear?-, but the careful work of the Staff at the Florid i 

 State Ai^riculcural E.vperiment Station has recently 

 brought their economic importance into cotislderable 

 prominence and has stimulated investigations on the 

 subject in several countries. 



As at present known, there are four species of funjjl 

 parasitic on scale insects in these islands, namely, the red 

 beaded, the white headed, and the black fungi, with a species 

 on shield scales, lleference has been made to these from 

 time to time in the A;/riculfii)nl J\'eii:<, but it is thought that 

 a short summary of the subject, with a description of the 

 superficial appearance of these fungi, an account of their 

 distribution and the methods that can be employed to s[iread 

 them, may not be out of place. 



THE RED HEADED FUX(U's [Sphaerostillje cocco- 

 ■phihi). This fungus has long been known as a parasite 

 on many forms of scale insects, and on white fiy. Its 

 delicate white mycelium attacks and kills the insect, 

 leaving it dry in appearance and, usually, easily detach- 

 able I from the leaf or stem on which it was growing. 

 The fungus then forms a very small red outgrowth from one 

 end of the insect : the outgrowth is usually more or less 

 elongated and bears on its upper surface numerous sickle- 

 shaped, hyaline, qnadricellular spores. This is the conidial 

 stage of the fungus. Later, it becomes darker in colour and 

 produces on a red stroma numerous small hemispherical 

 boxes or perithecia in which the ascos[>ores are borne. The 

 ascospores are oval, hyaline and bicellular. 



The fungus has up to the present been found in Domi- 

 nica, St. Lucia and Grenada on the white snow scale 

 (Cliiomispis citri), on limes ; on the black line scale 

 ( /schnaspis filiformis), on Finis sji.; iind on tlie purple scale 

 (.]f>/ti7iixj)ix rltricola), on limes. It is stated that in Florida 

 this fungus can do a large amount of damage to scale insects 

 without being visible to the naked eye, and it seems probable 

 that the same is the case in these islands. 



THE WniTK HEADED FUNGUS {Ojihioncctvia COCcictl/a). 



This fungus forms a white, knobbed outgrowth from 

 the dead scale, and bears on the surface of the knob 

 very numerous quadricellular spores, three of which 

 are usually united together at the base on a common 

 .stalk cell. The later stage consists of numerous, slightly 

 brownish boxes of perthecia, similar in shape to those 

 of the rod headed fungus, borne on a brownish stroma and 

 containing the multicellular ascospores. It has so far only 

 been found in Dominica on the puri)le scale on the leaves 

 of a citrus plant. It is, however, found frequently in Florida 

 and its distribution is probablymore generalin theWestlndies. 



THE CLACK FUNGUS {Myri(uvii)iiii Duriaci). This 

 fungus forms black crusts on branches of trees, more 

 especially lime trees infested with the white snow .scale 

 and the purple scale, and has been found in St. Lucia 

 and Barbados. The black crust, or stroma, grows out 

 from the scale and contains in its substance softer areas 

 of colourless cells in which the asci are sunk. These are 

 more or less spherical and contain eight nuilticellular brovvn 

 spores. The fungus must not be confused with black 

 blight, from which it is easily distinguished by its limited 

 extent, and thicker, more definite a]ipearance. 



THE SHIELD .SCALE FUNGUS. This forms a slightly buff- 



coloured fringe round several species of shield scales (Leca- 

 niuni), including tbe brown shield scale {L. heinisphen'riim), 

 the mango shield scale (Z. luam/iferaa), the soft shield scale 

 (L. hexperidiua), the green scale (Z. viride). The scales 

 become dry and p-ipery, and are eventually covered with 

 a buff-coloured growth of this iungus and its spores, in 

 addition to the fringe that spreads out all round the scale, 

 from underneath it. The appearance is characteristic, and 

 when once seen, not easily mistaken. It has so far been 

 found in Barbados, St. Vincent and Grenada. 



These are the main si)ecics found up to the present ; but 

 it seems probable that further investigations will reveal the 

 presence of one or two more forms, as well as the more 

 general distribution of those already observed. Most 

 of them, with the possible exception of the last, prefer 

 fairly moist conditions, and it is probable that the 

 growing of Bengal beans as a .shade for limes in Mont- 

 serrat has favoured the development of the red headed 

 fungus. (See Af/rifidtural A'ei"s, Vol. VIII, p. 1-54.) Where 

 these useful parasites are known to exist, an occasional 

 spraying with clean water, of the tree on which they are 

 growing, would help tliem to tide over a dry season and 

 enable them to establish themselves more vigorousl}' on 

 the scale insects as the number of these increases. The 

 fungi may be spread very sinqjly. If a tree is known 

 to contain them, branches showing the fungi may be 

 cut off and tied into the upper branches of those which it is 

 desired to infect ; the spores will then be carried by rain, 

 wind or insects to the scales on neighbouring branches and, 

 when once established under .satisfactory conditions, the 

 fungus will keep the .scale well in check. 



For the purpose of aiding in distribution, also, experi- 

 ments are in progress at the Head Othce of the Department 

 for the purpose of obtaining cultures of these fungi on 

 various nutrient media, for distribution to the Botanic 

 Stations. The fungi can be wa.shed off the medium into 

 about a quart of water, and the spores and portions of 

 mycelium sprayed on to the trees infected with scale insects 

 by means of a clean sprayer. When once established, the 

 fungi can be further spread by means of the tying method 

 already described. 



From what has been .said, it will be evident that the 

 fungi are doing much useful work in keeping these in.sect 

 parasites in check, and it is hoped that they mny be turned 

 to even better account in the future. In connexion with 

 this, another result of some importance which might be 

 expected to follow the reduction of the numbers of scale 

 insects is a perceptible diminution in the amount of black 

 blight. This fungus (C'lpnodium sp.) follows the scale insects 

 and, according to the generally accepted account, lives on the 

 'honey dew' secreted by them. (See A'/ricu/turnl A^ews, 

 Vol. VII, p. 161.) 



Any information with regard to the distribution ar.d 

 hosts of any of the species of fungi described above, or the 

 possible presence of new species would be acceptable, and 

 should be communicated to the local officers of the Depart- 

 ment. In theAi/riridtKiul Xeios, Vol. II, p. 32, there is a repoi't 

 of the presence of the red headed fungus and an unidentified 

 form, prohsMy Sporotyichiiiii, in Dominica, on the white snow 

 and purple scales; and on p. 216, of what is probably 

 Sporotrichum on the brown and mango shield scales in 

 Antigua. Vol. X, p. 42, of the same publication contains 

 a reference to the presence of red headed fungus, and 

 probably Sporotrichum, on white snow and purple scales in 

 Dominica. In Vol. VIII, pp. 186 and 202, several details 

 and a complete account of the methods of .spreading the 

 fungi are given. 



