A CATALOGUE OF THE TROMBICULINAE, OR CHIGGER 

 MITES, OF THE NEW WORLD, WITH NEAV GENERA 

 AND SPECIES AND A KEY TO THE GENERA 



By H. E. EwiNG 

 Entomologist, Bureau of Entomology, United States Department of Agriculture 



Interest in chigger mites has been greatly increased in recent years 

 by the discovery that they are concerned in the transmission of 

 certain typhuslike diseases of man. This interest, although largely 

 confined to medical men, has nevertheless so stimulated work on 

 the taxonomy of the group that to-day there are known to science 

 about 100 species. These are nearly all recently described and have 

 been reported from most of the larger geographical units of the 

 warmer regions of the world. They have been described by about 

 a dozen scientists and in a much larger number of scientific journals, 

 so that the time is now rather opportune for bringing together into a 

 single paper some of the more important taxonomic data dealing with 

 chiggers. Some of these taxonomic facts are here presented in the 

 form of a synopsis of the known genera and others in the form of an 

 annotated catalogue of the species of the New World. In addition, 

 descriptions are given of 2 new genera and 11 new species. 



The term " chigger mites " has been applied by the writer in the 

 past, and is applied by him in this paper, to those acarids of the family 

 Trombidiidae whose larvae parasitize vertebrates. The term " chig- 

 ger," however, should be restricted to the larval form of a chigger 

 mite. Rearing experiments indicate, so far as known, that all these 

 vertebrate-infesting larvae of Trombidiidae are the young of adults 

 that belong to the genus Tromhicula Berlese, in the original sense in 

 which this genus was used. The boundaries, therefore, of the sub- 

 family Trombiculinae should be restricted to those given originally 

 by Berlese to his collective genus Trombicula. 



No. 2908.— Proceedings U. S. National Museum, Vol. 80. Art. 8. 



70404—31 1 1 



