Nemastoma lugubre, Müller.
„ chrysomelas, Hermann.
Trogulidae.
Anelasmocephalus cambridgii, Westwood.
Trogulus tricarinatus, Linn.
CHAPTER XVIII
ARACHNIDA EMBOLOBRANCHIATA (CONTINUED)—ACARINA—HARVEST-BUGS—PARASITIC MITES—TICKS—SPINNING MITES—STRUCTURE—METAMORPHOSIS—CLASSIFICATION
Order IX. Acarina (Acari, Acaridea).
Arachnids with unsegmented,[[349]] non-pediculated abdomen. Respiration by tracheae, or by the general surface of the body. Month parts suctorial, but frequently capable of biting or piercing. Metamorphosis always observable.
The Acarina or Mites are remarkable not so much for the number of their species, which is very considerable, as for the vast multitude of individuals of the Order, which is far in excess of that of any other Arachnid group. This fact is correlated with their minute size. Very few Mites exceed half an inch in length, while very many are microscopic creatures, often measuring less than the hundredth of an inch. Taken all round, a millimetre may be considered a large size for a Mite.
There is much variety of habit within the Order. All Mites live principally on fluid nutriment, but it may be obtained from living animals or plants or from decaying organic matter. Some are entirely parasitic upon plants or animals; others attach themselves to animals in their larval stage, but are free when adults; while others, again, live an entirely independent and predaceous life.