288 OBSERVATIONS ON INSECTS. 



keeping them off; as it is generally supposed that 

 the object for which common poultry and other 

 birds dust themselves is that of ridding themselves 

 from these vermin, or preventing their accumulat- 

 ing. 



MITES.* 



Tick (Ixodes). WHILST examining a blue tit- 

 mouse (Parus coeruleus), I was surprised to find 

 under its feathers a specimen of a tick, nearly equal 

 in size to the dog-tick,-)- and to all appearance iden- 

 tically of the same species. One would hardly ex- 

 pect to meet with so large a parasite on so small a 

 bird.J 



On the same bird were large numbers of a very 

 minute sort of mite, so small indeed as to be scarcely 

 visible to the naked eye. I examined some of them 

 with the microscope, and found to my astonishment 

 that they consisted of several distinct species, refer- 

 able in some cases to distinct genera. This led me 

 to reflect on the numberless tribes of minute beings 



* Acarida; thought by some to constitute a peculiar class 

 among the Annulosa, but more probably only a subdivision of the 

 class Arachnida. 



f Ixodes ricinus, Leach. 



J Dr. Leach, in a paper published in the eleventh volume of 

 the Linnean Transactions, has described the British species of 

 Ixodes , one of which (I. pari) is mentioned as found on the great 

 titmouse (Parus major). This species I have myself taken from 

 that bird ; but it is quite different from the one noticed above, and 

 much smaller. 



