=AC′ARI= (-rī). [L.; prim. Gr.] _Syn._ ACAR′IDANS; ACAR′IDES (dēz); ACARID′IÆ. (-e-ē). In _entomology_, a division of arachnidans, including the _mite_ and _tick_. All the species are either microscopic or extremely minute, and possess such tenacity of life as to resist for some time the action of boiling water, and to live with comparative impunity in alcohol. Leuwenhoek had one that lived eleven weeks glued on its back to the point of a needle, without food. The following are well known——ACARUS AUTUMNA′LIS, the _harvest-bug_ or _wheal-worm_; A. DOMES′TICUS, the _domestic tick_; A. DYSENTE′RIÆ, the _dysentery-tick_; A. FARI′NÆ, the _meal mite_ (fig. _a_); A. RI′′CINUS (rĭc-), the _dog-tick_; A. SAC′CHARI, the _sugar-mite_ (fig. _b_); A. SI′′RO, the _cheese-mite_ (fig. _c_); A. SCABIE′I, the _itch-insect_ (fig. _d_). The irritation of the skin, caused by these vermin, may be relieved by a lotion of equal parts of sal volatile and water; and they may be destroyed by tobacco water, or a lotion or ointment of stavesacre. See ITCH, MANGE, PARASITES, PEDICULI, SCAB, &c. =Acarus Farinæ=, or _meal-mite_ (fig. _a_). This insect is found only in damaged flour, and is more frequently met with in the flour of the _leguminosæ_ (beans, peas) than in that of the _gramineæ_ (wheat, rye, oat). Now and then a single acarus may occasionally be found in good flour, but even one should be regarded with suspicion, and the flour should afterwards be frequently examined to see if they are increasing. [Illustration: FIG. _a._ Mag. 250 diams.] =Acarus Sacchari=, or _sugar-mite_ (fig. _b_). [Illustration: FIG. _b._ Mag. 260 diams.] Most of the brown sugars of commerce are infested by this pest, which is of a size sufficiently large to be visible to the naked eye. The following method of proceeding will lead to its detection: Dissolve 2 or 3 teaspoonfuls of sugar in a large wineglass of tepid water, and let the solution remain for an hour or so, at the expiration of which time the acari may be found, some on the surface of the liquid, some attaching themselves to the sides of the glass, and some at the bottom, mixed up with the copious and dark sediment, made up of fragments of cane, woody fibre, grit, dirt, and starch granules, which usually subside on dissolving even a small quantity of sugar in hot water. When first hatched this acarus is hardly visible. Acari of all sizes——that is, in all stages of growth——may be met with in most samples of sugar. Dr Hassall, in seventy-two samples of sugar which he examined, found sixty-nine containing them. [Illustration: FIG. _c._]