Mosquitoes and Parasite Problems. 145 



insects with their 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 bhe 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 



