INSECTS, MITES, ETC. 267 



water, will effect the same object. Plants in pots should 

 never be stood on the bare soil, but on tiles, slates, boards, 

 or cinder ashes, otherwise worms will readily gain ingress 

 to the roots. 



Yellow Orchid Aphis (Siphonophora lutea).— 

 Aphides, with greenish-yellow bodies, that infest orchids 

 grown under glass. There are winged and wingless 

 females. 



Remediei^. — Fumigation with nicotine compounds. 



* CHAPTER II. 



DISEASES OF GREENHOUSE PLANTS. 



Brown Spots and Holes in Leaves — Aspidistras 

 and palms sometimes have brown spots or holes in their 

 leaves. These are caused by careless sponging or by a 

 Shot Hole Fungus (Cercospora species). 



Remedies. — Always use a soft sponge, quite free from 

 grit. Never attempt to polish the leaves with oil rags, as 

 is sometimes done, and see that the roots are kept in as 

 healthy a condition as possible; then there will be few, if 

 any, brown spots or holes in the foliage. 



Camellia Diseases. — The bleached silvery-white 

 blotches, sprinkled with black spots, and sometimes seen 

 on camelhas, are caused by a fungus called Pestalozzia 

 Guepini. Another fungus. Camellia Black Mould (Macro- 

 sporium camellicTe) also forms similar blotches, but with 

 a definite brown margin. 



Remedy. — Pick off and burn diseased leaves. 



