230 HARVEST-BUGS. HYDRACHN^J, OR WATER-MITES. 



as in the Ixodes, Fig. 454,) so firmly in their skin, that they 

 can hardly be detached by force, the portion of skin to which 



FIG. 454. IXODES FIG. 455. a, HYDRACHNA GLOBULUS ; 



PLUMBEUS, AND ITS b, magnified ; c, young larva ; d, pupa. 



BEAK, magnified. 



they are attached coming away with them. It is probably the 

 young of a species of this group, which is commonly known as 

 the Harvest-Bug ; this is very common in the autumn, upon 

 grass or other herbage; and insinuates itself into the skin 

 at the roots of the hair, producing a very painful irritation. In 

 this state it possesses only six legs. Lastly, there is a tribe of 

 Acaridae, the Hydrachncz, in which the legs are covered with 

 hairs, in such a manner as to adapt them for swimming ; these 

 are all, during a part of their lives at least, parasitic upon 

 various Water- Insects, such as the Dytiscus, the Nepa, &c. 

 These Water-Mites undergo a more complete metamorphosis 

 than any of the preceding ; for the larvae have a very large 

 head, and six legs ; whilst the pupse have but a single pair of 

 legs, with which they attach themselves to the bodies of 

 insects, and present the appearance of an oval bag with a narrow 

 neck. 



