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.[24] 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 of 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,”[25] 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.”[26] 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.