INSECT “ BLIGHTS AND BLESSINGS.” 
129 
the Green Fly, whose dried skin then forms a protection to the 
chrysalis of the parasitic Fly, which when mature bites a circular 
hole in the skin (fig. 23) and escapes to continue its species in 
due course. There is a large field open to anyone desirous of 
studying the parasitic Hymenoptera of the British Aphidae. 
If I did not know it to be a fact, I should not venture to say 
that the disease known as “ The Black Currant Gall ” is utterly 
unknown to a large number of gardeners having hundreds and 
Fig. 21. 
thousands of trees under their care ; and yet every bush has 
been more or less affected, the common excuse for the scarcity 
of fruit being “ Oh! the birds take them.” It is not to be 
expected that gardeners should know the Gall Mite, which is but 
the one four-hundredth part of an inch long ; but every gardener 
in Great Britain ought to know the “ gall ” itself—a sketch of 
which I give at figs. 24 and 25—a photograph of twigs showing 
innumerable galls of from a quarter to three-eighths of an 
inch in diameter, much resembing a hard-hearted cabbage. 
