THE ICHNEUMON FLIES. 
293 
are made in the same tree. The nests are well and carefully- 
made of mud, roots, and grasses, about four inches in depth, 
and warmly lined with horsehair and very fine grasses. The 
fact that the bird possesses this capability of nest-building, 
gives more interest to the occasional habit of sharing its home 
with the osprey — a privilege of which it seems to avail itself 
whenever an osprey’s nest is within reach. 
The colour of this bird appears at a little distance to be black, 
but is in reality a very deep purple, changing in different lights to 
green, violet, and copper, and having a glossy sheen like that of 
satin. 
We now pass to the Parasitic Insects. As this work is in- 
tended to describe dwellings which are in some way formed by 
the creatures, it is necessary to exclude all the parasite insects 
that may exist upon the animal, and make no habitation, such 
as the ticks, as well as those which are merely parasitic within 
the animal, such as the various entozoa. 
Of Parasitic Insects, the greater number belong to that group 
of hymenoptera which is called Ichneumonidse, and which em- 
braces a number of species equal to all the other groups of the 
same order. Being desirous of producing, as far as possible, 
those examples of insects which have not been figured, I have 
selected for illustration several specimens which are now in the 
British Museum, one or two of which have only been recently 
placed in that collection. 
The best known of all the Ichneumonidae is that tiny creature 
called Microgaster glomeratus . 
A group of these insects and their cells is now before me, and 
will be briefly described. 
Small as it is, this tiny insect is extremely valuable to us, and 
to the gardener is beyond all value, though, as a general rule, 
the gardener knows nothing about it. Where it not for this 
ichneumon, we should scarcely have a cabbage or a cauliflower 
in the garden; for the noisome cabbage caterpillars would 
destroy every leaf of the present plant, and nip the growth of 
every bud which gave promise for the future. 
