Hawaiian Yellow-Faced Bees

by Dr. Sam Gon III, Director of Science

Of the over 10,000 native species found in Hawai`i, the clear majority, some 8,000 species, are invertebrates, and most of those are arthropods: insects, spiders, etc.

Insects in particular are important parts of the total ecosystem. They provide food for birds, feed on native plants (and each other!), process and create soil, and pollinate many native plant species.

One particularly important group of pollinators is Hawaiian yellow-faced bees (genus Hylaeus). These are small black bees often with a little patch of yellow on the front of their heads between the eyes. They were remarkably successful in ancient times, found in habitats from coast to subalpine, and in every imaginable vegetation type, where they busily collected pollen and nectar to feed their young. In so doing, they pollinated many of the plants, from `ōhi`a trees to low-growing herbs. Hawaiian yellow-faced bees are solitary bees, that is, they don't build communal hives of hundreds of individuals but each bee digs an underground nest or finds a hollow under the bark of forest trees, depending on the species. There she lays her eggs and provides pollen and nectar for her young.

A Bee Expedition
There are many different Hawaiian species of Hylaeus, and at least 15 of these have been reported from the island of Lāna`i, where we conducted a Canon grant-funded expedition in search of them. It was an open ticket to explore the island's varied habitats, from inland riverbeds to coastal dunes, or from the wet native forest on the summit, to the dry forest stands at Kanepu`u. It was a very dry summer, perhaps the driest in recent memory, as we went through an intense El Nino season in 1998. Perhaps that is why we ran into the bees only in two spots: in native koa forest near the summit of the island, and in dry shrublands near the coast. There appear to be two species, but of course we were disappointed not to find more of the 15 historically recorded species. Perhaps if we look again during a wetter year, we might find more of our native bees, busily buzzing about native plants, playing the ecological role that they've played for millenia. 

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