374 
FERNS : BRITISH AND FOREIGN. 
being the most subject, while, on the contrary, the 
smooth-fronded kinds, such as the whole of the 
division of Eremobrya, Elaphoglossum, &c., are, it 
may be said, quite exempt. The mealy bug, three 
kinds of scale, and thrips, are the chief pests, and 
should be carefully watched. The oblong brown 
scale is generally the most common, and very quickly 
overruns the under side of the frond, forming lines 
along the midribs. Many kinds of fluid mix- 
tures, powders, and other nostrums, have from time 
to time been advertised for their destruction, but it 
too often happens what kills insects also injures the 
plant, and makes it look unsightly. Fumigation 
with tobacco is the grand preventive against the 
breeding of plant-insects ; very slight fumigation 
destroys the winged male insect of all the Coccos 
family, and if frequently repeated, the whole in time 
will become extinct. When the mealy bug gets a 
head, it is readily got rid of by syringing; not so 
the scale, it requires to be loosened with a soft 
brush, or blunt-pointed peg, which, if the weather 
permit, should be done out of doors, and the plant 
afterwards syringed, so as to clear away all loose scale 
and eggs. Scale insects are adherers and suckers 
only ; not so the less conspicuous insect the thrip, 
which is a small, slender, black, shining insect, with 
large prominent eyes, and quick in its movements, 
herding in groups, generally on the under side of 
the frond, voraciously feeding on the cuticle, which 
they soon destroy, permanent injury being often done 
without any indication of their presence till too late ; 
they must, therefore, be carefully watched, and, when 
seen, at once destroyed by pinching with the fingers. 
