MITES AND TICKS. 
243 
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, Limnocliares, 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 ( Pontcirachna ) 
are marine. The next family (Holacaridce) 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. 
1, beetle-mite, Gamasus coleoptratorum (much enlarged) ; 2, dob beetle, rpi lTiav be obtained 
either by dredging m deep 
water or in rocky pools upon the coast. Passing on to the family Gamasidce, 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; 
Right-hand figure, water-mite ( Atax spinipes), 
seen from below ; Left - hand figure. 
water-scorpion, infested with Atax. 
