Marvels of the Universe 601 
often badly infested with a mite nearly related to 
that found on the Dor-beetle, which I described 
and illustrated in an earlier article; but in this 
case it is tolerably certain that their mission is 
not to attend the toilet of their host so much 
as looking after their own wants; for when they 
are hungry they are pale in colour, but when their 
digestive organs are full, they are of a purplish 
hue, a colour produced by the blood of their victim 
which they have consumed. 
Nevertheless, it should not be assumed that 
all the parasites of birds are undesirable guests. 
There are insect and mite organisms which are 
designated ‘‘ feather and hair eaters,’ and many 
of these render good service to their hosts by 
thinning their body-plumage during hot weather. 
The slender-bodied parasite of the duck shown 
amongst the illustrations, which may also be 
found on the goose, is an example of that order. 
Pigeons and doves also seem particularly favoured 
with this class of parasite; while other species 
patronize the fowl, teal, turkey, etc. 
It is a remarkable fact, too, that when several 
genera infest one host they confine their atten- 
tions to particular localities. Perhaps some will 
inhabit only the feathers of the neck, others those of 
the breast, and still others those of the wing 
feathers. They can move with remarkable facility, 
and have a way of turning sideways round the 
quill of the feather when touched ; and they can 
also travel as readily backwards as they can for- 
wards. These features combined with the fact 
that their bodies are flat and polished, make their 
chances of being caught when amongst the feathers 
very improbable. 
The mites (which are much smaller, and may 
be distinguished by their eight legs) are more 
nearly related to the spider family ; the six-legged 
parasites being insects properly speaking. Almost 
every bird species has one or more kinds of these 
organisms allotted to it, and some of them are, 
indeed, weird-looking animals when viewed through 
the microscope, the third pair of legs of the 
male sometimes being exaggerated into monstrous 
organs. Occasionally six-legged forms are dis- 
covered, but these are the mites in their larval 
stage ; after the final moulting of their skin eight 
legs appear. 
Although, as previously stated, some mites prey 
Photo by} (7. S. Cheavin, F.R. M.S 
BLACKBIRD PARASITES. 
It is a remarkable fact that when several kinds of 
parasites infest the same host each species usually confines 
itself to a particular locality. 
eS 
pee a 
Photo bu) (Ui J. Ward, F.ES. 
THE PARASITE OF THE TAWNY OWL. 
This “tick ’’ is an exception to the rule that all 
parasites are slender-bodied. Notice that it possesses eight 
legs instead of the usual six in all insects 
