Spiders and Their Near Relatives 



their blood. This pest can be destroyed by spraying the poultry 

 houses with kerosene. 



All of our species are now included in the family Gamasidae 

 of which nearly fifty species have been described representing 

 eighteen genera. 



Superfamily ORIBATOIDEA (Or-i-ba-toi'de-a) 



The Oribatid Mites 



The oribatid mites are now classed as a single family, the 

 Oribatidae; this is a large one, nearly one hundred and fifty species 

 being known from North America alone. Nearly all of these were 

 described by either Mr. Banks or Mr. Ewing; the number of 

 species will doubtless be greatly increased when our fauna is more 

 thoroughly explored. 



In most cases these mites are distinguished by the presence 

 of a pair of large club-shaped setae arising from near the pos- 

 terior corners of the cephalothorax 

 (Fig. 65). These setae are known 

 as the pseudo-stigmatic organs, from 

 the fact that the trichopores from 

 which they arise were formerly 

 believed to be spiracles. 



With most of the Oribatidae 

 thecuticula is coriaceous, giving the 



. . . Fig. 65. AX ORIBATID MITE 



mites some resemblance in appear- {H opiodema sphmda) tafter Banks) 

 ance to small beetles. For this 



reason they are sometimes termed "beetle mites"; but as this 

 name is often applied to those gamasid mites that are found on 

 beetles it is not distinctive. 



The resemblance of the oribatid mites to beetles is increased 

 by the fact that the suture separating the cephalothorax and 

 abdomen is usually quite distinct. Many of the common forms 

 are shining black in colour. 



These mites are of little or no economic importance; some of 

 them are supposed to injure grass to a slight extent; but most 

 of them are found among moss, on the bark of trees, and on the 

 ground under wood, bark, stones, and fallen leaves. .Most of 

 the species feed on vegetable matter, a few are found on decaying 

 animal matter, and some bore into decaying wood. 



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