INSECTS THAT INFEST ORCHIDS. 53 



.INSECTS THAT INFEST ORCHIDS. 



MOST plants are subject to insect pests, although, it is not 

 often that they do any serious damage, that is, if ordinary 

 precautions are taken by the cultivator or his assistants to 

 prevent injury. Thrips is one of the worst, especially if the 

 temperature of the house is excessive and the atmosphere 

 dry; but in the houses devoted to cool Orchids this ought 

 never to be the case. The cool, moist atmosphere of the 

 Odontoglossum house is not the most favourable for insect 

 life. Eed spider sometimes, though rarely, makes its appear- 

 ance in a dry corner, and if there is a yellow thrips in the 

 house it is almost certain to commence operations on the juicy 

 foliage of Cypripedium Schlimmi. The yellow fly, so common 

 in Orchid houses, will infest the flower-spikes of Odontoglots 

 and Calanthes, but two or three moderately strong doses of 

 tobacco smoke will clear them out. Tobacco rag, i. e., the old 

 coverings of the rollers used in the manufacture of " twist," 

 is far preferable to the vile rubbish sold as tobacco paper, and 

 the chances of burning are considerably reduced by its use. 

 In smoking Odoiitoglossums great care must be taken, or 

 the smoke will do serious damage. They should never be 

 subjected to smoking if in the least degree shrivelled by a hot 

 and dry atmosphere. Mr. Culley, who has charge of the 

 well known collection of " Cool " Orchids at Ferniehurst, never 

 hesitates to smoke his Odontoglots, but it must be remem- 

 bered that their bulbs and foliage are fresh and plump, in 

 which condition it rarely harms them, though Mr. Bateman, 

 whose name in connection with Orchids is well-known, strongly 

 objected to the use of tobacco smoke in the Odontoglossum 

 houses. 



Orchids grown in cool houses rarely suffer from the small 



