СНАРТЕК Х 
FERN FOES AND REMEDIES 
As in every case where plants are grown under glass vermin of 
various kinds are sure to make their appearance, it is as well to 
devote a short chapter to the methods of dealing with them. 
The principal foes we have in our mind are Green-fly, Aphis, 
White-fly, Aleyrodes vaporaria, and the Weevil, Otiorhyncus sulcatus, 
plus, in houses where artificial warmth is provided, Thrips. The 
presence of Green-fly is almost invariably due to insufficient ventila- 
tion or overshading, which induces a tenderness of growth and un- 
healthy conditions; healthy plants appear fully capable of resisting 
their attacks. The first remedy is therefore better ventilation, 
avoiding draughts, and an increase of light if possible. In this 
latter connection removable blinds are better than fixed ones, 
since the more daylight there is admitted the stronger the growth, 
and shading is really only necessary against blazing hot sunshine 
and during the warmest months of the year. The second remedy 
we shall come to later. The White-fly is a terrible infliction when 
once it is allowed to obtain a footing. This is a fly, really of a very 
light lemon colour, which flits about snipe fashion from plant to 
plant when disturbed, and has a clever knack of alighting on the 
under side of the fronds at a point distant from its apparent point 
of settlement. Its flight, too, is remarkably swift, and as we have 
indicated, erratic. This fly attacks both deciduous and evergreen 
Ferns, but only lays its eggs on the fronds, so that those laid on 
deciduous ones are eventually cleared away and the following 
season's brood only arises from those left on persistent ones. Its 
attack takes the form of a gnawing away of the epidermis or skin 
of the foliage, the result of which is tortuous lines of dirty white, 
which in bad cases pervade the fronds entirely and weaken the 
plants considerably. The eggs, in cold houses, hatch out about 
April, when the larve or immature flies may be found on the backs 
of the discoloured fronds as tiny whitish insects, already busy with 
their gnawing, and capable of creeping to fresh fields and pastures 
new on the same Fern even at this stage, though their wider ex- 
cursions are deferred until May, when after a short chrysaloid 
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