UPON SCALE-INSECTS. 55 



to micro-fungi says, " In this country micro-fungi are only 

 occasionally destructive to coccids, and so far as my experience 

 goes only infest those species found on plants under glass." 

 Again, " I have not met with a single instance of an outdoor 

 coccid in this country being attacked by a fungoid disease. 

 But future research may prove they are not immune from 

 such attacks." 



As a rule these fungi cause epidemic diseases amongst 

 the scale-insects they attack, few scales on a plant or group 

 of plants escaping. They appear spasmodically when the 

 conditions are favourable and rapidly spread over the coccids 

 infesting any particular plant or crop. In Java and Ceylon 

 the green-bug (Lecanium viride) has been noticed to be 

 affected in epidemic fashion by Cephalosporium over large 

 tracts of coffee. In Florida Aschersotiia aleyrodis has been 

 observed by Webber to spread rapidly over the mealy wing 

 (Aleurodes citri) on the orange. Microcera can also cause 

 epidemics amongst the San Jose Scale (Aspidiotus perni- 

 ciosus). A remarkable example quite recently brought to 

 notice occurred in the island of Martinique. The cocoanut 

 palms were suffering severely from an attack of a coccid, 

 closely allied to the S. Jose Scale. A fungous disease 

 suddenly appeared and spread with such rapidity amongst 

 the scales as practically to save these trees from probable 

 destruction. 



Considering how few scales escape, and how difficult it is 

 sometimes to find a single unaffected insect on a leaf pos- 

 sessing the fungus, it is quite possible that many fungi 

 described by systematists in the past, as growing on the 

 surfaces of leaves and stems, might have had scale-insects a 

 their true hosts. For example, it is probable that the genus 

 Aschersonia at first considered a leaf-fungus is really in the 

 main or wholly entomogenous. In the recognized coccido 

 phagous forms the scale is so enveloped by the stroma of 

 the fungus, that its remains can only be seen with the aid 

 of sections and a microscope. As already pointed out 

 Aschersonia is probably the conidial stage of Hypocrella ; 



