DISEASES AND INSECTS. 



<>5 



The plants most likely to be attacked are those which are sometimes excited by too 

 much heat and moisture, and at other times checked, this alone being sufficient to 

 induce spot. Other causes are decomposed and sour materials in the compost, decayed 

 blocks or baskets, and a stagnant atmosphere. 



Plants of good constitution, and otherwise healthy, are seldom troubled with " spot," 

 and should they by careless treatment become affected, they usually overcome it when 

 again properly cultivated. Timely attention to all cultural details, then, is at once 

 the preventive and cure for this disease, which will always run riot in badly managed 

 collections. 



Insects. 



If orchid diseases are few, the insects that attack the plants are many. Perfect 

 immunity from insect pests is a desideratum very unlikely to be attained ; but by the 

 use of improved methods of fumigation and insecticides growers are far nearer it 

 than formerly. 



Aphis or green fiy often appears, especially on plants coming into flower. If so 

 numerous as to make fumigation necessary, use the XL All, or some other of the nicotine 

 vaporisers now on the market. Full directions as to the use of these are sent with the 

 necessary materials, and although the initial cost is rather higher than when the old- 

 fashioned method of fumigating with tobacco paper or rag is practised, the safety and 

 efficiency of these modern methods should insure their universal adoption. If only a 

 few insects are present, they may be easily removed by passing a damp sponge over the 

 flower-spikes, leaves, or pseudo-bulbs, as the case may be. 



Ants are not destructive, but are unsightly and unwelcome in orchid houses. They are 

 attracted in many cases by the presence of aphis and other insects upon which they feed. 

 If their nests can be found, pour very hot water into them. This will kill many of the 

 invaders, and if persisted in will drive the others away ; petroleum and camphor are also 

 banishing agents. 



The Cattleta Fly. — This attacks cattleyaE and leelias, the eggs being deposited by 

 the flies in the soft immature eyes or buds of the plant. The maggots resulting destroy 

 the tissues of the issuing growths, and cause them to become abnormally swollen. 

 The growths when once attacked are quite useless, and should be cut off as soon as seen 

 to be swelling unduly, and burnt forthwith. If this is done early, there is a chance of 

 getting a healthy break from the same pseudo-bulb ; if left, the perfect insect pre- 



VOL. III. k 



