106 



ACARINA OR MITES. 



red-spider of fruit, the Bryobia pruni, can thus be readily seen to 

 be acari and not araneida. Nearly all acari produce ova : some 

 few are, however, parthenogenetic, and produce living young. 

 The foUowing are the groups of some importance to the farmer 

 and gardener : — 



(i) TromliididoB, the so-called Spinning Elites or Red-spiders. 

 These are found on the leaves of plants, and constitute the 

 group Tefranijchi (fig. 42), which can be told by their small 

 size and usually semi-transparent bodies, sometimes however 

 tinged with red. Closely related to these are the Harvest 

 Bugs (fig. 41), wliicli are generally of a brilliant colour, and 

 may be found under stones, earth, 

 &c., and sometimes, in some of their 

 stages, as very noxious human and 

 fowl parasites. 



(ii) The BdeUidtv or Snouted 

 Mites can be told by the long snout 

 and similar brilliant colourmg of the 

 body. Some are parasites on insects, 

 (iii.) The Gama-sidfi' (fig. 44) some 

 of which are also parasitic on animals 

 and birds, have usually some modi- 

 fication of the second pair of legs to 

 distinguish tliem. 



Ticks can always be told by their 

 leathery skin and by having a sort of shield on the back behind 

 the head. 



(v) The Oribatidce have a hard, chitinous, more or less 

 shiny skin, and are known as Beetle :Mites. These are often 

 very beneficial (fig. 47). 



(vi)jThe Acarida', colourless and nearly transparent, 

 (vii) The Sarcoptidw are the parasitic forms that produce 

 scab, scaly leg, &c., and have a more or less transverse wrinkled 

 skin and long suckers on some of the feet. 



(viii) The P/njtoptidw or Gall Mites, living in plants, are 



Fig. 41.— Harvest Bdo (Trom- 

 hidiuvi }ioloserii:eum). 



Adult of the Harvest Bug. 



(iv) The Ixodidit or 



