Introduction 9 



investigating the internal organs the ear, eye, anal, and genital open- 

 ings should be examined. Few mites are parasitic in the digestive tract 

 of animals, but some are associated with the respiratory systems of 

 both vertebrates and invertebrates. 



When animals suspected of harboring mites are brought into the 

 laboratory alive, many of the ectoparasites can be collected without 

 examining the host. Live hosts can be placed in cages that have wire 

 or hardware cloth bottoms so that mites that fall off will drop through 

 the floor of the cage. A suitable tray is placed beneath the cage from 

 which the parasites can then be collected. Feces and urine of the host 

 interfere frequently with this method but judicious feeding and fre- 

 quent examination and cleaning can overcome this difficulty. 



Figure 4 A Birge net. (Photo by Parker) 



There are two useful tools for collecting free-living water mites. One 

 is a smaff dip net with a narrow mesh bag with which mites that are 

 visible in the water can be scooped up and the other is a Birge net 

 (Figure 4). Water mites are to be found in practically all waters, but 

 the best collecting sites for them are smaU lakes, streams, and ponds. 

 In using the Birge net care should be exercised so that the bag remains 

 expanded in the water. The net is designed to be used in weedy areas 

 so that it snags infrequently. It is in the weedy areas along the shores 

 that most water mites live. 



Preparation for Study: Ticks can be studied satisfactorily without 

 mounting them on a glass slide. The taxonomic characters of ticks can 

 best be made out if the tick is studied with the aid of a fairly high- 

 powered dissecting microscope. 



Mites, on the other hand, must be prepared for examination by 

 transmitted light and a compound microscope. Therefore they must 

 be cleared and mounted on a glass slide. Many methods have been 



