The endemic Hawaiian sap beetles are extremely diverse ecologically. The vast majority of species are found in high elevation native mesic and wet forests. They can be found on a wide variety of flowering plants and ferns, as well as in decaying organic material. They are recorded from 65 genera in 45 families of flowering plants, and 7 genera in 5 families of ferns. Some species are monophagous, some are oligophagous and some are polyphagous.

They can be found on all above ground parts of flowering plants. They are found on fresh living leaves, flowers, and fruit, and on all parts in a state of decay. They consume nectar and pollen from fresh flowers, and presumably consume yeasts from decaying material. Historically they were found commonly at sap fluxes, especially those of Koa tree, but very few have been collected from this habitat since the 1930's.

On ferns they consume spores and decaying fronds of many of the most common species. They prefer tree ferns and low species that grow in thick clumps such as Athyrium and some Dryopteris species.

Decaying plant material supports populations of fungi and bacteria. The Hawaiian Drosophila are found on many of the same substrates as the Hawaiian Nitidulidae. The two groups subdivide the resource, with the Drosophila consuming bacteria and emerging first and the nitidulids consuming fungi and eclosing after the Drosophila. An association between the flower inhabiting endemic Hawaiian Nitidulidae and the ascomycete yeast genus Metschnikowia has been documented. Ephemeral flowers provide an opportunity for close fungi/beetle associations to develop. The relative sterile nectary of a newly opened flower is inoculated by the beetles with giant Metschnikowia ascospores delivered through the beetles gut. As the yeasts multiply within the flower the vegetative cells are consumed by the beetle.

Glossary

Monophagous: Animals that are associated with a single host.

Oligophagous: Animals that are associated with a small number of often closely related hosts.

Polyphagous:  Animals that are associated with a wide variety of distantly related hosts.