60 TWTUUN : FUNGI PARASITIC 



attack the immature coccid larvae, which at first are sheltered 

 by the old mother scale, and then escaping lead a brief free 

 existence before fixing themselves permanently to the plant. 

 The inseoi may possibly pick up the fungus spore during it* 

 short active state. 



X at urn I Means of Dispersal. 



Fungus spores are most commonly carried by the wind. 

 For many of these coccidophagous fungi, this can hardly be 

 the case. The conidia of Nectria (Fusarium), Microcera, 

 (■ephalosporium, and others, are held together by soluble 

 mucilage, so in these cases rain and dew must act as distri- 

 butors to some extent, though owing to scale-insects being 

 usually attached to the lower side of leaves, the fungi upon 

 them are not so readily wetted by rain, nor can their spores 

 be so easily carried by it from one leaf to another. 



Considering the rapid spread some of these fungi have 

 been observed to make in orange groves ami coffee plantations 

 affected by scale pests, they must have some quick means of 

 distributing their conidia. Webber, in dwelling upon this 

 point, suggests ants as a means, especially since such insects 

 air in tin' habit of visiting those coccids which excrete honey 

 dew. Ants are exceedingly common in the tropics. He 

 also suggests that they may be attracted too by the brightly 

 coloured conidial masses of the Aschersonia. Of course this 

 idea about ants could not well apply to coccids of the 

 sub-family Diaspidinese which do notexcretehoney dew, and 

 are therefore not visited by them. 



In Ascomycetes, as a rule, the conidia serve the purpose 

 of Increasing the fungus in the area in which it has estab- 

 lished Itself : they are produced in great abundance, germi- 

 quickly, and soon lose their vitality. The ascospores 

 serve rather to start new colonics elsewhere ; they 

 only appear towards the end of the life of the fungus and 

 retain their vitality for a long time. This may also be the 

 with th« COOOidophagOUfl fungi, such as Nectria which 



