INSECT ENEMIES. 299 
fungi. This disease is at times very destruc- 
tive. 
A host of insects also attack plants and produce 
disease more or less injurious to them. Every 
one who has had a rose-tree under his care, must 
have noticed occasionally a general unhealthiness 
of appearance steal over the plant, many of the 
leaves drooping, and the branches ceasing to 
grow. On turning up the leaves, there will gene- 
rally be found a thick crowd of green insects 
which are feeding with all their might upon the 
pleasant sap of the young shoots. These are 
called Aphides, and if not checked they will 
ultimately destroy the plant. The number of 
the different species attacking vegetables is alto- 
gether astonishing; and we are filled with wonder 
to find, that we really suffer from their attacks 
in our gardens, fields, and orchards, as little as 
we do, when we remember how easily their num- 
bers might be multiplied, and how awful have 
their devastations been on _ special occasions. 
More than once have the desolations produced by 
a caterpillar humbled great nations, and brought 
crowds into the house of God to entreat Him 
to remove the plague from the land, and this 
