Introduction 3 



available on them. The one suborder of the Acarina — the ticks — that 

 is readily visible to the unaided eye is well studied. Students of ticks 

 know them as well as the entomologists know the larger insects. They 

 can be studied effectively without special techniques. A dissecting mi- 

 croscope or even a high-powered hand lens will reveal the important 

 taxonomic features. With other Acarina this is not the case. Techniques 

 foreign to the entomologist must be used, and special methods of col- 

 lecting are required. Specimens must be mounted on microscopic slides 

 and studied under magnifications as high as one thousand diameters. 

 Furthermore, the techniques are not the same as those used in various 

 zoological sciences, although many special methods are borrowed from 

 both zoology and entomology. The Acarina are not small enough to be 

 handled like protozoans or soft-bodied enough to be treated as worms 

 and they are too small to be studied like insects. Therefore they have 

 been ignored by zoologists and entomologists alike. 



Many individuals would explain our lack of information on the 

 mites on the basis of their relatively insignificant importance. This is 

 not the case. At present many groups of mites that are of known 

 economic importance are poorly understood. As knowledge of mites 

 increases the vital, practical significance of many species will be rec- 

 ognized. The science of acarology holds the same position today that 

 entomology held fifty or one hundred years ago. 



History: Mites and ticks have been recognized for a long time. The 

 early Greek writers were familiar with ticks and a few mites. In fact, 

 Acari is the Latinized form of the Greek word for mite. By the time of 

 Linnaeus, however, only about ninety species had been discussed in 

 the literature, and the tenth edition of the "Systema Naturae" included 

 only some twenty-nine species of mites in the genus Acarus. By 1850, 

 however, many species were recognized. Oudemans 1926-1937 in his 

 ''Kritisch Historisch Overzicht der Acarologie" covers the literature up 

 to and including 1850. Oudemans' work is invaluable to anyone de- 

 siring information on early publications concerned with mites. 



From 1850 to the present time most work of a general nature has 

 been done in Europe. Nalepa, G. and R. Canestrini, Berlese, Troues- 

 sart, Hirst, Michael, Oudemans, Vitzthum, Thor, Tragardh, and others 

 have made valuable contributions. Andre, Grandjean, Lundblad, 

 Sellnick, Willmann, and Viets are still publishing important works. 

 In the United States only two general acarologists have been active 

 during most of the present century, although several have contributed 



