INSECTS AND THEIR NEAR RELATIVES. 43 



transverse, fine lines, which are so impressed as to appear 

 like the divisions between minute segments (Fig. 52). The 

 majority of mites are very small ; but some, as certain Ticks, 

 are of considerable size. 



With the exception of a single family the members of 

 which bring forth living young, all mites are produced from 

 eggs. As a rule, the newly-hatched mites have only three 

 pairs of legs; but a fourth pair are added during growth. 

 In Phytoptus, which infests plants, there are only two pairs 

 of legs. 



The mode of life of the different members of this order 

 varies greatly : some are parasitic upon animals ; others 

 infest living plants ; and many feed upon dead animal or 

 vegetable matter, thus acting as scavengers. 



Among the mites that are parasitic upon animals are the 

 various Ticks, which are very common in the 

 warmer parts of our country. Figure 50 rep- 

 resents the Cattle-tick of the Southern States. > ^/i'*fC*l 

 It should be remembered in this connection 

 that the so-called Sheep-tick is a true insect, FIG. S o. The 



, , . , j TV Cattle-tick, fe- 



belonging to the order Diptera. male. 



The Itch-mite is a well-known parasite, infesting man 



and causing the disease known as 

 the itch. The sensation character- 

 istic of this disease is due to the 

 burrowing of the mites in the skin ; 

 and the efficiency of sulphur oint- 



F.G. si.-An Itch-mite :"a, from ment in checking this disease is 



below; b, from above. due to the fact that by the use of 



it the mites are killed. Figure 51 represents an itch-mite 

 greatly enlarged. 



Parasitic mites are frequently found attached to insects ; 

 a common species occurs beneath the wings of locusts. 



The best known of the mites that infest plants is the one 

 commonly called the Red Spider. This lives upon house- 

 plants ; and in the warmer parts of the country, where there 



