PEAR MITE. 



117 



hooks and a serrated labium (a). These parts form a beak 

 which the mite or tick insinuates into the flesh of its host, upon 

 the blood of which it subsists. While many of the mites are 

 parasitic on animals, some are known to devour the eggs of 

 insects and other mites, thrusting their beaks into the egg, and 

 sucking the contents. We have seen a mite (Nothrus oviv- 

 orus, Fig. 143) busily engaged in destroying the eggs of a moth 

 like that of the Canker worm, and Dr. Shinier has observed the 

 Acarus? malus sucking the eggs of the Chinch bug. I have 

 also observed another mite 

 devouring the Aphides on 

 the rose leaves in my gar- 

 den, so that a few mites 

 may be set down as bene- 

 ficial to vegetation. While 

 a few species aro injurious 

 to man, the larger part are 

 beneficial, being either par- 

 asitic and baneful to other 

 noxious animals, or more 

 directly useful as scaven- 

 gers, removing decaying 

 animal and vegetable sub- 

 stances. 



The transformations of 

 the mites are interesting to the philosophic zoologist, since the 

 young of certain forms are remarkably different from the adults, 

 and in reaching the perfect state the mite passes through a 

 metamorphosis more striking than that of many insects. The 

 young on leaving the egg have six legs, as we have seen in the 

 case of the Ixodes. Sometimes, however, as, for example, in 

 the larva, as we may call it, of a European mite, Typhlodromus 

 pyri, the adult of which, according to A. Scheuten, is allied to 

 Acarus, and lives under the epidermis of the leaves of the pear 

 in Europe (while Mr. T. Taylor, of the Department of Agricul- 

 ture at Washington, has found a species in the pear leaves about 

 Washington, and still another form in peach leaves), there are 

 but two pairs of legs present, and the body is long, cylindrical 



142. Ixodes albipictus and young.* 



< The figure at the bottom on -the left represents the adult, fully-gorged tick. 



