The rare O'ahu picture-winged fly Drosophila ambochila Hardy
& Kaneshiro is endemic to two windward ravines in the Wai'anae Mountains
that harbor its host plant. Drosophila ambochila is an ecological specialist that
breeds on Pisonia stems and trunks in an intermediate stage of decay. By providing
field-collected females with suitable substrate material, we have been
able to observe the oviposition behavior of this species in the laboratory and
obtain F 1 larvae. In nature, females oviposit each batch of mature eggs ("'4050)
in a single cluster, by repeatedly inserting their long ovipositor into the
same crack or beetle hole in the decaying Pisonia bark. Ovipositor, ovary, and
egg morphology are characteristic of bark-breeding Hawaiian Drosophila, but
SEM studies revealed a distinctive chorionic ultrastructure for the eggs of this
species. Larval salivary chromosome analyses indicated that the O'ahu D. ambochila
is most closely related to D. alsophila from the island of Hawai'i and
have helped to resolve the phylogenetic relationships among six of the nine species
belonging to the vesciseta subgroup of the glabriapex species group
