12 JAMES BURTON ON A SPECIES OF ALEURODES. 



far away from its first position. In the next stage it has settled 

 down, and thrown out a delicate fringe of waxy filaments round 

 the lower edge of the body, which seems to fix it to the leaf. It 

 now much resembles a Scale-insect. From this stage it appears to 

 increase in size, and develops a number of long glass-like brittle 

 processes from the back and sides, about twelve in number, and 

 becomes box-like, oval in outline, with sides of considerable depth ; 

 the side of the box is composed chiefly of the wax fringe, and the 

 edges are ornamented with curved glass-like hairs, shorter than 

 those already spoken of. The imago becomes gradually more 

 clearly visible in this which is the pupa stage ; at last the top of 

 the box is rent, usually across, but sometimes the lid is forced off 

 at one end, and the fly emerges a beautiful and delicate little object, 

 especially for the binocular microscope. I have tried to dry 

 them for opaque illumination, but they shrivel up and become 

 distorted and useless. 



Like the green flies and the Scale-insects, no doubt Aleurodes 

 does damage to plants by sucking their juices, and when the 

 number present is great of course the damage would be consider- 

 able. But another, though somewhat indirect injury results from 

 the presence of any of these insects. The honey-dew secreted falls 

 chiefly on the upper surfaces of the lower leaves of the plants upon 

 which they are living, or upon the leaves of any plants growing 

 beneath them, and this honey-dew forms the substratum upon 

 which one or more species of fungi flourish. Mr. Massee in his 

 Text-hook of Plant Diseases refers to the sooty mould following 

 the white fly Aleurodes citri. One species is recorded as attacking 

 coconut trees, and is named Aleurodes cocois. A. hrassicae and A. 

 proletella both occur on cabbages, while A. citri is very injurious 

 in many parts of the world on trees of the Citrus group, doing 

 great damage to orange and lemon fruit. Mr. Lewis's specimens 

 occurred on a species of Asparagus, apparently grown for orna- 

 mental purposes in Natal. The sooty fungus Fumago vagans is 

 extremely common, flourishing on the honey-dew secreted by the 



