CHIGGERS — FARRELL 223 



no adequate information of taxonomic significance has been de- 

 rived from the larger habitat situations. Most species appear to 

 be associated with forests. E. diversa seems to be associated with 

 meadows or thickets. E. blarinae appears to be independent of 

 any particular cover type and occurs wherever shrews are found. 

 From the host records it might be inferred that certain species, 

 such as E. marmotae or E. pipistrelli, have a different ecology. 

 However, available information concerning habitats is too general 

 for use in diagnosing species. 



When the hosts of the Euschongastia included in this paper are 

 considered, it is found that the chiggers usually parasitize small 

 mammals. Only E. nunezi has been found on birds (fowls) . Only 

 E. lacerta has been collected from a cold-blooded host. When host 

 relationships are considered more closely for those species which 

 have been collected a number of times, certain host patterns 

 become apparent. Occasionally there seems to be some host 

 preference. One large group of chiggers is found on two or more 

 of the smaller rodents — Peromyscus, Clethrionomys, Synaptomys, 

 and others. These chiggers include E. peromysci, E. cordiremus, 

 E. mibra, E. magna, E. criceticola, E. ohioensis, E. crateris, E. 

 carolinensis, and E. setosa. Euschongastia diversa also is found 

 on smaller rodents, but the list differs to include Microtus, Zapus, 

 and Napeozapus as important hosts, perhaps reflecting a dif- 

 ference in habitat. Another group of species is found on the 

 large rodent, Marmota. These chiggers include E. luteode7na, 

 E. marmotae, and Euschongastia sp. E. sciuricola has been col- 

 lected from chipmunks and squirrels. E. pipistrelli and E. hamil- 

 toni have been found only on bats. E. blarinae, except for the 

 type specimen, has been collected entirely from shrews. These 

 differences in host distribution seem to have diagnostic im- 

 portance, although records are insufficient for comprehensive 

 statements. At the present time it seems that E. blarinae can be 

 separated from the similar E. setosa on the basis of the host rec- 

 ord; but, because of the peculiar status of the type specimen of 

 E. blarinae, morphology should always be included in this diag- 

 nosis. 



Certain problems involving host relationships have already 

 been discussed. These include the case of the type specimen of 

 E. blarinae, the host relationships of the similar E. carolinensis 

 and E. ohioensis, and the correlation of morphology with host 

 preference of E. luteodema and E. marmotae. The host difference 

 between E. sciuricola and Euschongastia sp. has been considered. 

 It was, in fact, the host difference — the one, arboreal ; the other, 



