Mosquitoes aud Parasite Problems. 145 
insects wifcli tlieir beaks before they have penetrated 
into the skin. I believe they are also able to pro- 
tect themselves in another way, namely, by prevent- 
ing the parasites from reaching their bodies at all. 
I was out under the trees one day with a pet oven- 
bird (Furnarius rufus), which had full liberty to 
range about at will, and noticed that at short inter- 
vals it went through the motions of picking some- 
thing from its toes or legs, though I could see 
nothing on them. At length I approached my eyes 
to within a few inches of the bird’s feet, and dis- 
covered that the large dry branch on which it stood 
was covered with a multitude of parasites, all run- 
ning rapidly about like foraging ants, and whenever 
one came to the bird’s feet it at once ran up the leg. 
Every time this happened, so far as I could see, the 
bird felt it, and quickly and deftly picked it off with 
the point of its bill. It seemed very astonishing 
that the horny covering of the toes and legs should 
be so exquisitely sensitive, for the insects are so 
small and light that they cannot be felt on the hand, 
even when a score of them are running over it ; but 
the fact is as I have stated, and it is highly probable, 
I think, that most wild birds keep themselves free 
from these little torments in the same way. 
Some observations of mine on a species of Orni- 
thomyia — a fly parasitical on birds — might possibly 
be of use in considering the question of the anomalous 
position in nature of insects possessing the instincts 
and aptitudes of parasites, and organs manifestly 
modified to suit a parasitical mode of life, yet com- 
pelled and able to exist free, feeding, perhaps, on 
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