HAWAII NATURE NOTES
THE INSECT LIFE
Basic data for this section prepared under the supervision of D. Elmo Hardy, Entomologist, University of Hawaii, to whom grateful acknowledgement is made.
Hawaii National Park is rich in insect life although, as is typical of insular areas, insects are much more sparse than in continental regions. Most of our insects are endemic species, i.e., are found only in these islands; many are very limited in distribution. For the most part the endemic insects are associated with the native plants. Most of our insects are comparatively small and inconspicuous; nevertheless, a great many are strange and unusual so that our fauna is particularly interesting to the scientist. We have none of the larger, showy butterflies and other insects which the visitor often expects to find here. No noxious or harmful species are present in areas used by park visitors, but the large blowflies which breed in goat carcasses in Haleakala Crater sometimes become a nuisance, due to their presence in large numbers. These are mainland species which have been accidentally introduced into Hawaii and which are now restricted to the highland areas where the climate is temperate. With the exception of lice and domestic flies, which were brought here by the Hawaiians themselves, Hawaii was free of pestiferous insects before the arrival of the Europeans.
One of the best known endemic Hawaiian insects is the butterfly named after King Kamehameha, Vanessa tameamea, a highly colored relative of the painted lady, the tortoise shells, and the red admiral butterflies of the mainland. This species is highly prized by amateur butterfly collectors since it is found no place else in the world. Its colors are orange, brown, and black. The female has small white spots in the apical portions of the front wings; these spots are rosy colored in the male. The caterpillars, green or purplish, feed on the leaves of the mamaki. Adults are found in forests throughout the islands. They are attracted to the native hydrangea, kanawao, to the introduced thimbleberry, or to the sap exuding from koa or naio. This butterfly is a strong flier, and ranges from the seacoast to the top of Haleakala. The female of Hodegia apetala, an endemic genus of only one described species, is an Hawaiian moth unable to fly.21 The male is unknown. This jumping insect, related to the bollworm, lives in bunch grass near the summit. The narrow, pointed, reduced, ashen-brown wings are 1/2 inch long; the abdomen, about as long as the wings, is brownish gray.
As one walks over open patches at higher elevations a brown moth, 1-1/22 inches wide, rises readily before one. This is Agrostis aulacias that possesses great powers of flight.22 The genus of 27 species is related to army worms, cut-worms, and a host of agricultural pests. Fletcherana insularis is a geometrid moth (inch worm, measuring worm, or looper) found in late spring high above the forest belt near the park entrance. The insect is an inch wide, its color is white, speckled with black. The genus of 5 species is confined to Hawaii.
Nesophrosyne haleakala is a mottled, gray-brown leafhopper, 1/8 inch long; the head and front part of the thorax are yellowish. In the park it is found in pilo and ohelo at 8,500 or 9,000 feet. The genus is endemic and contains over 60 forms distributed throughout the islands.
An undesirable pest has publicized its presence high above the park entrance by leaving its name on two caves which early visitors found convenient for shelter. Big Flea and Little Flea Caves often appear in accounts of early trips, but never without mention of the annoyance that was caused by their permanent occupants. Of the 7 different kinds of fleas recorded for Hawaii, only the so-called cat flea (Ctenocephalides felis) annoys people to any extent. Several species of fleas infest the Hawaiian rat and were presumably brought in when this rodent arrived with the earliest Polynesian immigrants.
Because the beautiful silversword has no very close relatives, which means that its ancestors arrived in Hawaii in earliest time, any species of insects associated solely with it as a host plant draws particular interest. Moreover, since the survival of silverswords is precarious in this day of rapid change, all agents that threaten must be carefully scrutinized. Silverswords are specific hosts to a half dozen or more endemic species of insects.23 Among Lepidoptera, the family of moths and butterflies, the larvae of a pyralid moth, Rhynchephestia rhabdotus, feeds in the flower-heads, destroying the seeds. Caterpillars of a noctuid, Euxoa epicremma, have been collected beneath plants. The caterpillars of a tineid moth have been found among dead leaves. Of the DIPTERA, great numbers of yellow maggots of a gray fly, Tephritis cratericola, feed on the seeds and prevent their development. The larvae of one of the Coleoptera, a beetle described as Aescheithmysus terryi, feeds apparently only on old and dead stems. A relative, A. swezeyi, similarly feeds on Railliardia. Great members of a leaf-hopper, Iburnia argyroxiphii, suck the sap of Haleakala silverswords. It is preyed upon by a wasp, Polynema sp., so tiny that the naked eye can hardly see it. The wasp lays its egg in the egg of the hopper. The larval wasp, upon hatching, feeds on the contents of the hopper egg, pupates within it, and emerges from it.
The Paliku area is very rich in insect life; many hundreds of species have been recorded from here and many are apparently very restricted in distribution and are known only from this locality. Species of pomace-flies (DROSOPHILIDAE) and the long-legged flies (DOLICHOPODIDAE) are especially prevalent at Paliku. Two species the native genus Idiomyia are the largest members of DROSOPHILIDAE found any place in the world; they measure approximately 7 mm. in length. Two species of flightless Neuroptera (Pseudopsectra cookeorum and lobipennis) occur on the vegetation (Dubautia, Metrosideros, and Cyanea) in Haleakala; these represent one of the strangest entomological curiosities of the world.
Over five thousand species of insects have been recorded from the Hawaiian Islands and it is probable that several thousand more species remain to be described. In the past our knowledge of the insects was based largely upon the monumental study, "Fauna Hawaiiensis,"24 published by a group of institutions including the British Museum (Natural History) and the Bernice P. Bishop Museum. A new faunistic study is now under way titled "Insects of Hawaii."25 This is an extremely valuable reference work and is indispensable to anyone studying Hawaiian insects. It gives a complete review of the insects from the lowest orders through the butterflies and larger moths. Two volumes on the DIPTERA are now in press. Volume one gives a most comprehensive account of the mode of dispersal of our endemic fauna and flora to these islands. It is estimated that the 3,722 known endemic insects developed from approximately 250 ancestral species.
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