MITE. 
463 
it has once fixed itself, as to be scarcely separated 
without violence; its motion, when disengaged, is 
pretty quick, though by no means equal to that of 
some other Acari. On the part where it fixes it 
causes a tumor, generally about the size of a pea; 
sometimes mucli larger, accompanied by a severe 
itching. These insects abound on vegetables, and 
are generally contracted by walking in gardens, 
amongst long grass, or in corn fields. 
According to Mr. White, in his History of Sel- 
borne, they abound to an uncommon degree in 
the chalky districts of that part of Hampshire. 
He relates that he lias been assured that the war- 
reners, in the chalky downs, are so much infested 
by them, and that they swarm to so infinite a 
degree as to discolour their nets, and give them a 
reddish cast, while the men are so bitten as to be 
thrown into fevers. 
Among the larger species of this genus may be 
numbered the Acarus Ricinus, or Tick, so fre- 
quently seen on dogs, and sometimes on cattle: it 
often arrives nearly to the size of a small bean, 
and is of a livid brown colour, with paler and 
darker variegations; this animal is furnished be- 
tween the antennas with a strong, broad, and flat- 
tened snout or proboscis, edged on both sides by 
a row of strong, sharp, reversed prickles, which 
serve, when once introduced into the skin, to ad- 
here with such a degree of tenacity as not to be 
easily removed. 
Acarus Reduvius is of a. similar nature to the 
V. VI. P. II. 
30 
