Our Llvini^ Ri'soura's — Hawaii 



S65 



Insects are the dominant animals in most ter- 

 restrial ecosystems, especially on isolated 

 oceanic islands where many larger animals are 

 absent. In Hawaii, many of the original coloniz- 

 ing species evohed into perhaps 10,000 or more 

 new species and adapted to live in the diverse 

 island habitats. In addition to their importance as 

 pollinators of native plants, recyclers of nutri- 

 ents in ecosystems, and food for native birds and 

 other animals, insects are also excellent subjects 

 for evolutionary research. The isolation and 

 habitat diversity of the Hawaiian Islands make 

 them wonderful natural laboratories for studying 

 ecology and evolution. Many important research 

 projects have featured Hawaiian insects, such as 

 the native Drosophila {see Foote and Carson, 

 this section) and crickets (Otte 1989). 



Because insects are important components 

 of ecosystems, insect surveys can be used to 

 assess the health of native ecosystems, and 

 reserve managers often need to be able to deter- 

 mine the status of insects to properly manage 

 other natural resources. Such assessments, how- 

 ever, are daunting tasks: although about 5,100 

 native insect species have been described in 

 Hawaii, probably at least as many more remain 

 undescribed or unknown. In addition, about 

 2,600 insect species have been established 

 through human activities. Many native species 

 are declining from the combined effects of inva- 

 sive non-native organisms and human alteration 

 of habitats. 



Information on the status of Hawaiian 

 insects came from a data base compiled at the 

 Bishop Museum of all published records on the 

 taxonomy, biology, and distribution of 

 Hawaiian arthropods (Nishida 1992). Further 

 infomiation on the status and trends of selected 

 rare species was obtained from label data of 

 preserved specimens, especially those in the 

 research collections at Bishop Museum and 

 University of Hawaii, Honolulu, as well as 

 from personal communications and observa- 

 tions of researchers in the field. Population sur- 

 veys are in progress to determine the status and 

 trends of a few insect groups such as the dam- 

 selflies (Megalagriorr. Polhemus 1993) and 

 cave species. 



Insects of Hawaii 



Only 16 out of 30 insect orders recognized 

 worldwide are represented in the native fauna. 

 Another 1 1 orders have become established 

 through human activities (Figs. I and 2). The 

 beetles (Coleoptera), flies (Diptera), bees and 

 wasps (Hymenoptera), and moths (Lepidoptera) 

 are the largest groups in the Hawaiian Islands. 

 Most native species are found on the high, main 

 islands, but each of the northwest Hawaiian 



Islands harbors a few interesting species (Fig. 

 3). Oahu currently has the most known species, 

 but this stems from collecting bias because most 

 entomologists have lived and worked on Oahu. 

 Maui and Kauai, in particular, should have com- 

 parable numbers. Western Maui, for example, 

 was missed in the early insect surveys, and its 

 insect fauna remains poorly known. About 63% 

 of the species occur on only one island, and 

 many have extremely restricted ranges within 

 their island. This limited distribution and lack of 

 information on how many species there are and 

 where they survive have important conse- 

 quences in planning for their conservation. 



Trends 



Profound changes are occurring in the 

 Hawaiian insect fauna. Increasing contact with 

 the outside world has broken the isolation that 

 allowed the evolution of native species. The 

 changing composition of the Hawaiian insect 



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Insects of 

 Hawaii 



by 

 Francis G. Howarlh 



Gordon Nishida 

 Bishop Museum, Hawaii 



Adam Asquith 

 U.S. Fish and Wildlife Service 



Fig. 1. Comparison of native and 

 non-native insects in the larger 

 orders (i.e., represented by more 

 than 75 species) in Hawaii. 

 Source: Hawaiian Terrestrial 

 Arthropod Database. February 

 1994. 



Fig. 2. Comparison of native and 

 non-native insects in the smaller 

 orders (i.e., represented by fewer 

 than 75 species) in Hawaii. 

 Source: Hawaiian Terrestrial 

 Arthropod Database. February 

 1994, 



