218 
Methods of Preventimj and GhecJcing 
of the enemies and parasites peculiar to crops. In this way the 
appearance of new insects and fungi in countries pi-eviously free 
from them is easily accounted for, but it is difficult to explain the 
reason of the exceeding increase of some of the pests of certain 
crops within the last half century, and the consequent serious 
injury occasioned by them. For instance, aphides have come 
regularly upon the hop plants during the last few seasons, and 
would have caused utter destruction if prompt measures had not 
been taken against them. Within the last ten years the cater- 
pillars of the winter-moth have become chronic pests in many 
of the apple-producing districts of England, having been until 
then the most occasional visitors in comparatively rare places. 
With regard to fungi, their development in the form of mil- 
dews, moulds, blights, and rusts is even more remarkable. Fifty 
years ago the potato disease caused by the fungus Fhytopldhora iv- 
festans was unknown in this country, and the vines in France and 
Germany were free from the O'iditnn Tuclieri, which has caused 
such great losses in all their vineyards. Since 1878 another 
mildew (Peronospora viticola) has sorely plagued European wine- 
producers. It was first noticed in France in the Charentes, and 
spread rapidly. The hop mildew (Podosphcera castagnei), though 
known in Kent before the curious and general invasion of 
mildews in 1843, has since then assumed a far more virulent 
and chronic nature, and has extended its attack to all the hop- 
growing counties. Since 1875 a mildew (Ilemileia vastatnx) 
has much troubled the coffee-planters in Ceylon, and within the 
last few years a mildew (Peziza WiWxommii) has seriously afl'ected 
larches in English and Scotch woods and forests. The apple and 
pear scabs (Fusidadium dendriticiim and Fusicladiwn pyrinurri) 
were not observed in Great Britain until after 1844. In some 
seasons since that date apples and pears have been greatfy dis- 
figured by the blotches, or black spots, upon them produced by 
these fungi. The apple scab (Fusidadium dendriticuin) was first 
noticed in Canada in 1882 ; also in Illinois, Wisconsin, and 
other American States where apples are cultivated. It prevails 
also in the apple orchards of South Australia, where it was 
first seen in 18G5 or 18G6. 
Among the most notable and calamitous visitations of insects 
of modern date, that of the Phylloxera vasiatrix, or vine louse, 
in the French vineyards stands prominent in respect of the injury 
occasioned and the enormous money losses sustained. It is 
estimated that from 1875 to 1887 the total loss to France 
amounted to more than 400,000,000/.' These figures are based 
' Let Imectei fie la Vigne. Par Va!6ry Ma3'et (1890). 
