74 COMMERCIAL ROSE CULTURE 



coloring of the leaf. These insects live on the underside of the 

 leaf; here they lay their eggs, which they protect with a fine 

 silken web, in consequence of which they are hard to destroy. 

 The best remedy is a good, sharp syringing on the under- 

 side of the leaves, taking care to reach every part to dislodge 

 them all. The water must be forcibly applied; it is ineffective 

 otherwise ; a pressure of 60 Ibs. to the square inch is good ; less 

 than 40 Ibs. is not enough. A thin, sharp spray is needed, un- 

 like the soft stream used when watering. Sulphur painted on 

 the pipes in sufficient quantity will kill red spider, but this must 

 be kept up for a week or so, as it does not affect the eggs which 

 hatch out and produce a new crop. The objection to sulphur 

 so strong on the steam pipes is that the color of the flowers is 

 damaged thereby and a few leaves may fall from the bushes, 

 but, beyond this, I have never seen any other harm from its use 

 in this way. 



A very hot, dry atmosphere in a Rose house is conducive to 

 the spread of red spider and the opposite condition has a deter- 

 rent effect. There are good articles on the market for use as 

 a spray against this pest which are worth trying; do not con- 

 demn them without a careful investigation. 



Thrips are small winged insects less than an eighth of an 

 inch long. The havoc wrought among the foliage by them is 

 similar to that caused by red spider; their presence is noted by 

 the pale mottling of the leaf on which they feed. They also 

 feed upon the buds and are partial to American Beauty. All 

 affected buds should be cut off and burned, and all dead leaves 

 and rubbish kept cleaned away. Fumigate regularly with 

 Nicofume, or similar article, and spray with a good tobacco 

 extract. 



Another remedy is to heat iron plates almost red hot; the 

 house must be closed tightly, as it must always be for any fumi- 

 gating to be effective. Set the plates about 25 feet apart and 

 provide two rows if the house is wide. Commence at the 



