MITES AND TICKS 179 



should be mounted on cardboard, in much the same way as a beetle, and 

 saturated with gumtragacanth, when it will keep fakly well. If it should 

 get covered with mould, a brushing with methylated spirits will remove it 

 instantly. 



Harvest Men (Phalangida). These long-legged animals might easily be 

 mistaken for spiders, but are distinguished by their segmented abdomens, 

 and the absence of a definite " waist " (the spider's abdomen has no segmenta- 

 tion). They have two eyes, large pincers, in addition to their long thin legs, 

 and feed upon plant-lice and other small insects. 



MITES AND TICKS 



are related to spiders, but form a distinct order (Acarina). Most of them are 

 exceedingly small, and must be studied with a pocket lens or the microscope. 

 They have oval bodies, and there is no distinction between the cephalothorax 

 and the abdomen. In the adult forms there are eight legs, but some in their 

 earlier stages have only six. The mouth may be an organ for biting, but 

 usually it is adapted for sucking. Some are found in water, others on land. 

 Many are parasites living on the blood of their hosts, others infest insects, 

 still more feed on decaying matter. 



Almost any pond will yield specimens of a minute scarlet mite (Hydrachna) 

 very active in swimming, with eight legs thickly fringed with hairs. The female 

 makes a puncture in the leaves of pond-weed, and deposits its eggs therein 

 in May or June ; from these a red larva with six legs emerges. The mite 

 is a parasite on water beetles in the next stage, driving its sharp beak into the 

 body of its host. Here it often appears to lose or absorb its legs, and grows 

 in size until it becomes the adult eight-legged free swimming Water Mite. 



Another mite (Gamasus coleoptratorum) is exceedingly common on beetles 

 and bees. Examine a Watchman Beetle, or a Humble Bee, and frequently you 

 will find it covered underneath with these creatures. The so-called " RED 

 SPIDER " is in reality another mite most destructive to plants. 



The Cheese Mite (Tyroglyphus siro) is another familiar species, the larvae 

 having three pairs of legs, and passing through a " nymph " or pupal stage 

 with eight legs before assuming the adult form. 



The Harvest Bug, which so torments people with delicate skins, is really 

 the larva of the mite Trombidium holosericeum. It is a bright scarlet, but so 

 small as to be hardly visible to the naked eye. The eggs are laid in June 

 and July, and produce a six-legged larva, almost round, which finds a host to 

 live on, and thrusts its sharp mandibles into the skin. Then it swells to nearly 

 five times its original size with the fluid it imbibes, drops off and hibernates, 

 turning next spring into an eight-legged nymph, which feeds upon vegetation 

 only. 



