CHAPTER XIV 



WATER-MITES 



Hydracarina 



Fonn.— Water-mites are small, brightly colored relatives 

 of the spiders. They have eight legs like them and at 

 first glance their bodies seem to have the same form. How- 

 ever, those of water-mites are in a single piece (Fig. 135) while 

 spiders have two distinct sections, a fused head and thorax 

 and the abdomen. The group of Acarina, or mites, to which 

 water-mites are related contains many parasites, some of them 

 associated with such diseases as itch, mange, and spotted 

 fever. 



Most water-mites are brightly colored, dark red, scarlet, or 

 sometimes orange (PI. X). They are all small, rarely more 

 than a quarter of an inch long. One of the largest of them, 

 the bright red Hydrachna (Fig. 137), is about the size of a 

 small pea. Others are only a little larger than the head of a 

 pin. 



Habits and habitat.— Although they breathe air and run 

 about on the surface film and over the border plants they can 

 stay under water for a long time. They live in the side waters 

 of quiet streams and in still pools where there is water the 

 year round. There they creep about on mud and sand 

 bottoms and over the submerged plants and dart through the 

 water with a peculiar sort of running glide. They are all 

 carnivorous feeders, and like spiders clutch their prey and 

 suck the juice from their bodies. 



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