SPIDERS, MITES, AND TICKS. 545 



Order VII. — Acaeina (Mites and Ticks). 



This large order includes a great variety of creatures. Most of them 

 are very minute, and many are almost microscopic. The cephaloihorax 

 and abdomen are fused together, the body forming a compact, rounded, or 

 oval mass ; the sexes are separate, and sometimes very different in appear- 

 ance ; the mouth is formed for biting or sucking, and there are nearly always 

 eight legs in the perfect state, but often six only in the earlier stages. The 

 Fhitopti have usually only four. Many of the species are more or less bristly. 

 Some feed on plants, and others on decaying animal and vegetable sub- 

 stances. A considerable number are parasitic. 



The BdelUdce are mites of a bright red colour, with a long snout, and long 

 palpi, which are generally elbowed, and have the appearance of antennae. 

 Some are found among moss, and others on the sea-shore; while others, again, 

 are parasitic on various insects. The number of eyes varies, and in some 

 cave-frequenting species, the eyes are obsolete. 



The Gamasidce are a family of mites, many of which are parasitic on insects, 

 and others on warm-blooded animals. They are without eyes, the mandibles 

 are piucer-like, and the legs are hairy, and furnished with 

 two claws. The first or second pair of legs are frequently Insect-Mites 

 much thicker than the others ; and the immature mites have {Gamasidce). 

 only six legs. The species of Gnmxnnis (Latr. ) infest different 

 kinds of insects, especially the black dung-beetles belonging to the genus 

 Geotrnpes (Fabr.), and its allies ; and they are also numerous on humble-bees. 

 They may often be found running over these insects ; but there are other 

 mites infesting beetles which are attached to their host by a thread ; these be- 

 long to the genus Uropoda (Latr.). Other mites of this family attack warm- 

 blooded animals, and are very numerous among poultry and caged birds, and 

 sometimes become troublesome to man by transference. 



The Halacariike are a small family of mites, living habitually under the 

 sea, having either a stiff, or a more or less rigid, cuirassed skin, and with 

 tlieir legs springing from the inner margin of the body. 

 They are found among sea-weeds in rook-pools, or are brought Marine Mites 

 up, sometimes in large numbers, by the dredge. The body (Halacaridm). 

 is oval, the snout more or less produced, and the palpi rather 

 long. 



The next family we have to consider is that of the Ifydrachiidce, or fresh- 

 water mites. These are round, or, more rarely, oval, and are generally 

 smooth and velvety, and of a red, black and red, or purple 

 colour. Most of them have only six legs when immature. Fresh-Water 

 They have a hook at the extremity of the palpi, and are Mites 



in the habit of attaching themselves to various water- (Hydrachnida;). 

 animals. 



The IxodidcE, or ticks, are among the largest and most troublesome of the 

 whole group. They are usually of an oval form, and have a tough skin, and 

 a mouth fitted for sucking. Some are provided with eyes, 

 and others are blind. They live on grass and herbage, and Ticks 



the usual habit of the fumale is to attach herself to any (Ixodida;). 

 warm-blooded animal, pierce the skin, and suck the blood 

 till she is gorged, when she falls off. They are sometimes very troublesome in 

 summer and autumn, even in England ; but in hot countries they are often 

 a terrible pest, especially in the Southern States of America, and in some 

 parts of South America, where they are particularly troublesome to cattle. 

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