J 52 Acarology 



23. Qimdracus Keifer, 1944 



Type. Quadrcicus urticae Keifer, 1944 



24. Rhyncaphytoptus Keifer, 1939 



Type. Rhyncaphytoptus ficifolicie Keifer, 1939 



25. 7^^o/7omjy Nalepa, 1890 



Type. Tegonotus fastigatus Nalepa, 1890 



26. Tetra Keifer, 1944 



Type. "Phyllocoptruta" concava Keifer, 1939 



27. Thafnnacus Keif QT, \944 



Type. Phyllocoptes rhamnicola Keifer, 1938 



28. Tumescoptes Keifer, 1939 



Type. Tumescoptes trachycarpi Keifer, 1939 



29. Vasates Shimer, 1869 



Type. Vasates quadripedes Shimer, 1869 



Unassigned genus: 



Flexipalpus Schcuten, 1857 



Type. Flexipalpus tiliae Scheuten, 1857 



Discussion: Not until Keifer's 1942 work on the alternation of gen- 

 erations in the buckeye rust mite {Oxypleurites aesculijoliae Keifer), 

 was the life cycle of certain of the eriophyid mites fully understood. 

 Yothers et al. 1930 had studied the citrus rust mite and Baker 1939 

 the fig mite, but both species belong to those having a simple life cycle 

 without alternation of generations. Keifer's study on the buckeye rust 

 mite has also solved the problem of the pear leaf rust mite, Epitri- 

 merus pirijoliae Keifer. 



One female of Oxypleurites aesculijoliae resembles the male and is 

 called the protogyne. The other female of this species is morphologi- 

 cally different from the primogyne, or primary type, and has no male 

 counterpart. This Keifer calls the deutogyne. Originally, owing to dif- 

 ferences in striation, the two forms had been described as different 

 species in different genera [Phyllocoptes aesculifoliae (protogyne) and 

 Oxypleurites neocarinatus (deutogyne)]. The Oxypleurite female, or 

 protogynes, when reared, produced both forms of females. Deutogynes 

 when reared laid eggs which gave birth to egg-laying protogynes. 



The following life history of the buckeye rust mite is taken from 

 Keifer 1942. 



The deutogynes become active in late winter, leave their hibernating quar- 

 ters on the twigs and when the buds swell in February, penetrate beneath 

 the outer scales; there they feed on the green tissue of the inner scales. 



