 The hen flea ( <unk> gallinae ) is the most common flea in their nests . The small , pale house @-@ sparrow flea C. <unk> , is also occasionally found there and probably arises from the habit of its main host of taking over the nests of other species . This flea does not occur in the US , even on house <unk> . <unk> include <unk> <unk> , <unk> <unk> and <unk> <unk> . Other <unk> parasites include <unk> ticks and mites such as <unk> <unk> , <unk> <unk> , <unk> gallinae , <unk> <unk> , O. <unk> , <unk> species , <unk> <unk> and <unk> <unk> . The hen <unk> D. gallinae is itself preyed upon by the predatory <unk> <unk> <unk> . The presence of this control on numbers of the parasitic species may explain why birds are prepared to reuse old nests . 
