MITES AND, TICKS. 



243 



Right-hand figure, water-mite (Atax spinipes), 

 seen from below ; Left - hand figure. 



WATER-SCORPION, INFESTED WITH A tax. 



upon plants, and obtain nourishment by sucking the sap. One of the best known 

 is Tetranychus telarius, a little red mite, sometimes called the money-spider. The 

 web it spins is of very fine texture, and may usually be found on the backs of 

 leaves, where it appears to be merely used as a protective screen for both adults 

 and young. The silk is secreted from a conical nipple situated on the under side 

 of the extremity of the abdomen, and, as in the case of spiders, is manipulated 

 by the appendages. Also related to the Trombidiidce, but connecting them 

 with the next family, is the common mud-mite, Limnochares, which lives in 

 fresh-water ponds, creeping upon the mud or the leaves of aquatic plants. The 

 larva adheres to various water-insects. The 

 water - mites (Hydrachnidce) have been 

 described as Trombidiidce that have adopted 

 an exclusively aquatic life. They live in 

 fresh -water ponds and streams, where they 

 may be seen swimming freely by means of 

 vigorous strokes of their legs, which act like 

 oars. In the adult the body is generally more 

 or less spherical, and usually of a bright red 

 or green colour. The males of one species 

 (Atax globator) have a curious blunt tail-like 

 prolongation from the hinder end of the 



abdomen. The eggs are laid in the spring, in the stems of water-plants which are 

 perforated for the purpose, and the six-footed larvae when hatched attach them- 

 selves to water - bugs (Nepa), or water - beetles (Dytiscus), by means of a large 

 sucker on the front of the head. The abdomen then starts growing, the feet 

 drop off, and the creature remains hanging like a sack to its host. One species 

 (Atax bonzi) lives in the shell of the fresh- water mussel, while a few (Pontarachna) 

 are marine. The next family (Halacaridce) contains marine forms differing from 



the last in many important 

 features ; the mouth-parts 

 being more united. In 

 addition to the pair of 

 eyes on the carapace, there 

 is an unpaired eye upon 

 the epistome. These 

 marine mites do not 

 appear to swim like their 

 fresh - water allies, but 

 creep on the stems of sea- 

 weeds and zoophytes. 

 They may be obtained 

 either by dredging in deep 

 water or in rocky pools upon the coast. Passing on to the family Ga,masidce, we 

 find the stigmata placed far back in the body, frequently at the sides of the thorax, 

 above the legs of the third or fourth pair. The beak is imperfectly developed, the 

 palpi being foot-like and free, and the mandibles pincer-like. There are no eyes ; 



1, bestls-mite, Gamasus coleoptratorum (much enlarged) ; 2, dor beetle, 



INFESTED WITH GamasUS. 



