170 



THE BOOK OF CHOICE FERNS. 



plants infested with thrips and red spider ; but, in nine cases out of 

 ten, when the same plants are subjected to a lower temperature, they remain 

 perfectly clean. The same remarks apply to a little white fly, commonly 

 called the " Tomato Fly," which is distinguishable from all others by its 

 peculiarly abrupt, erratic, short flight, darting instantaneously, when disturbed, 

 from one plant to another, and which almost invariably settles on the under- 

 side of the fronds. 



Of all the above-named insects, the thrips (Fig. 13) is the most dangerous, 

 for its depredations are swift and irreparable. In the cases of mealy bug, 

 scales, and flies, when the plants have once been freed from their presence, 

 they increase in vigour, and their appearance does not show any signs of the 

 passage of the enemy. With the thrips — which is a small insect, barely x Vin. 



long, white when quite young, and black when adult, 

 and possessed of wonderful destructive powers — it is 

 very different, for it feeds exclusively on the outer 

 coating of the frond on which it lives, leaving 

 behind it marks which nothing can remove. On 

 account of the delicacy of their texture, and of the 

 very fine nature of their foliage, the process of 

 F '\l^nJea) PS washing or sponging, which is practicable in most 



other classes of plants, is almost impossible in 

 regard to Ferns ■ other means of getting rid of these pests must therefore, 

 in most cases, be resorted to. Attention has already been called to the 

 greater liability to which Ferns grown in too high a temperature are subject 

 regarding the attacks of the thrips, which soon disfigure them entirely, and 

 which, when found only in small quantities, may be picked off the plants by 

 hand, and then be kept under by the said plants being subjected to a cooler 

 treatment afterwards. But if the Ferns have been allowed to get badly 

 infested with thrips, the only remedy lies in the application of tobacco- 

 smoke or, better still, of tobacco-vapour. A full description of the genus 

 Thrips is given in Nicholson's " Dictionary of Gardening," vol. iv., p. 30. 



Ferns, however, are, as a rule, very sensitive and very adverse to fumi- 

 gation, and when this operation has to be resorted to, it is far better to 

 smoke the house moderately in the evening, and repeat the operation the next 

 morning, than to smoke strongly at once. It is also preferable to smoke 



