Chapter 15 



Insects and Allies (Arthropoda) of 

 Enewetak Atoll 



G. ALLAN SAMUELSON and GORDON M. NISHIDA 



Bernice P. Bishop Museum 

 Honolulu, Hauxiii 9681 7 



INTRODUCTION 



Insects and related terrestrial arthropods of Enewetak 

 Atoll remain inadequately investigated. Woodbury (1962) 

 included an inventory of arthropods known from the atoll 

 in which he indicated that ectoparasites were taken from 

 10 species of birds; altogether he reported 45 species or 

 subspecies authentically recorded from the atoll. The 

 present list increases the number of arthropods to 191 

 species (or subspecies) and must still be considered prelim- 

 inary, as records are lacking for many expected groups. 

 Before this list can be completed, further collections and 

 their study are required, especially of the soil fauna, ecto- 

 parasites and nidicoles of reptiles, birds, and rodents, and 

 the forms associated with humans and human habitations. 

 A checklist of Enewetak insects and related arthropods is 

 provided in Table 1. 



Investigations 



Enewetak Atoll appears to have received little or no 

 attention from investigators of insects and other terrestrial 

 arthropods until the beginning of American occupation in 

 1944. Published records and dated specimens from earlier 

 times are either given without exact localities or refer to 

 other parts of the Marshall Islands. The relative isolation of 

 the atoll probably accounted for the inattention. Even dur- 

 ing the period of the Japanese Mandate, when insects 

 were collected elsewhere in the Marshalls and generally 

 throughout Micronesia, nothing was specifically included 

 from Enewetak. The entomological activities of the 

 Japanese during that period are best summarized in a long 

 series of pafjers reporting on results of Teiso Esaki's 

 Microncsian Exf)editions of 1936-1940 (cf. Esaki et ed., 

 1955). Entomological field work on Enewetak by Ameri- 

 cans began in 1944 and continued through the postwar 



years to the present. Surveys conducted by or with the 

 support of the military, the U. S. Commercial Company, 

 and the Pacific Science Board (PSB) gave considerable 

 impetus to establishing the series Insects of Micronesia in 

 1954. This series has become the most important source 

 for reporting on the Micronesian fauna. The earliest 

 account treating Enewetak insects is apparently Townes 

 (1946), a mimeographed report for the U. S. Commercial 

 Company, which contains records of about 20 S[>ecies. 

 The first such account published in a serial is apparently 

 Van Zwaluwenburg (1948) in which an elaterid beetle is 

 reported. Titles containing records of Enewetak insects and 

 allies are cited in the bibliography. 



Visits to Enewetak Atoll by entomologists and others 

 providing records of insects and related groups from the 

 atoll are outlined in Table 2. So far as is known, all of 

 these visits follow the period of Japanese occupation. 

 Spellings of the islets or motus are those currently used by 

 the Marshallese, and they may vary from names previously 

 used in gazetteers or in Bryan (1971). 



For a time, an insect collection assembled by L. D. 

 Tuthill was kept at the Mid-Pacific Research Laboratory 

 (MPRL) at Enewetak. Those specimens eventually went to 

 Bishop Museum for inclusion in studies repnjrted in Insects 

 of Micronesia. This collection, along with those conducted 

 under the auspices of the PSB, are to be ultimately depos- 

 ited in collections of participating PSB institutions: Califor- 

 nia Academy of Sciences in San Francisco, Field Museum 

 of Natural History in Chicago, Museum of Comparative 

 Zoology at Harvard University in Cambridge, and National 

 Museum of NatureJ History in Washington, as well as 

 Bishop Museum in Honolulu. 



Environment 



Enewetak Atoll is an isolated outlier on the 

 northwestern extremity of the Ralik Chain in the drier, 

 northern portion of the Marshall Islands. Vegetation is 

 accordingly poorer there than on the wetter, southern 

 atolls of both the Ralik and Ratak Chains (cf. Hathaway, 

 1953; St. John, 1960). A drier climate and a less diverse 

 flora would offer fewer niches for insects; thus one would 



147 



