Haleakala Crater: Native Insects of the Sub-Alpine Aeolian Desert

photo by Quang-Tuan Luong©

"Summer Every Day, Winter Every Night"

Haleakala Crater is a dormant shield volcano on the island of Maui. At an altitude of 10,023 ft. the climate is quite extreme, attaining daytime temperatures in the 80's - 90's, then dipping down into the 30's - 40's at night. Every few years there is the occasional snowfall that may stay on the ground for several days. This national park encompasses a variety of micro-climates, from desert to rain forest, but overall the main climate at the highest elevations is classified as sub-arctic aeolian desert. This is a harsh enviorment: barren, arid, often windy, with wildly fluctuating temperatures and conditions. In an amazing display of adaptive radiation, some descendants of species that made it to this island by wind, waves or wing, and survived, found their way up these slopes to make this raw place their home. Aeolian means wind, and many of the insects found in the crater are predators/scavengers, feeding upon debris and dead insects that are blown into the crater from lower altitudes. Many have become flightless, such as the flightless moths, lace wings and flies. Most of the lifecycles of these hardy insects and spiders revolve around the spectacular silversword, a relative of the sunflower, and found only here and on the Big Island craters.

The Silversword

The Haleakala Silversword, Argyroxiphium sandwicense ssp. macroephalum, is a spectacular example of adaptive radiation, and one of few plants able to withstand the harshness of the crater's intense solar radiation and aridness. It is descended from a humble North American tarweed, Raillard muril, that arrived on this island tens of thousands of years ago and found a virtual blank slate to exploit for survival, the family adopting many forms. The silversword species lives approximately 50 years before shooting out an incredible inflorescence, just that once, and then dying. Many of the aeolian creatures depend upon the silversword for their survival. Several endemic insects associated with the Silversword ecosystem are flies (Trupanea), bees (Nesoprosopsis), moths (Agrotis, Rhynchephestia), planthoppers (Nesosydne), and a cerambycid beetle (Plagithmysis). In turn, the silversword depends upon them for its survival. These insects are the pollenators of the silversword and without them the plant would eventually die out. As it is the Silversword are just starting to recover from teetering on the brink of extinction and are far from being a threatened species. Now, since the control of the ravages of alien introduced foragers, such as feral goats, in the park, one of the main threats to the native insects, and thus the silversword, is the spread of the Argentine ant. The Argentine ant, Linepithema humilis, is an alien species (all ants are alien; there are no native ants) that is a very agressive predator. There are several on-going projects concerned with the control of the ant problem. Another agressive alien predator posing a great danger to the delicate balance of this fragile environment is the yellow-jacket wasp, Vespula pensylvanica. When you find an ecosystem containing very few components, the more important each component becomes to the overall health and balance of that ecosystem. A great website to find out more about the silversword and all its fantastically diverse family in Hawaii is the Silversword Alliance page.

Meet Some of the Players:

One of the native species of the ground-nesting yellow-faced bees, Nesoprosopis volcanica, doing her important service of pollenating a silversword flower.

These moths, Thyrocopa apatela, in a strange twist of evolution, have lost their ability to fly. Resembling dead, dried leaves, these scavengers are blown into crevices that collect other organic debris blown up from lower elevations, upon which they feed. Their catepillers also feed on dead leaves.

This particular species of lacewing was last collected in 1945 before being rediscovered in 1994. It is known only in a small area of the crater near the summit. Its wings have become hardened and beetle-like and are not used for flight. Photo: © S. Montgomery, Montane Matters.

The larvae of this native Tephridid fly Trupanes sp. depend upon the fruit of the Silversword for their survival.

Although not generally found in the aeolian zone, the Blackburn Butterfly is found slightly lower in the sub-alpine scrub zone. Udara blackburni is one of only two native butterflies and has beautiful iridescent-green wing undersides and lavender on the tops.

The Koa Bug, Scutelleridae: Coleotichus blackburniae, an iridescent-hued true bug, is also found just below the aeolian zone, in the sub-alpine shrub, but is so beautiful it begged to be included! Like the Blackburn Butterfly, its favorite hosts are the Koa tree, Acacia koa and the `a`ali`i, Dodonaea viscosa.

Informative Links:

It is difficult to find any links about this specific subject, but here are some interesting and informative related links.

Insects of Hawaii
Good overview about the state of native Hawaiian insect species today, from a report by the U.S. Dept. of the Interior, Natural Biological Service.
Overview of the Pacific
From the same report as above, a wonderful summary of the Hawaiian Island`s overall ecological health, with some historical perspective and a few of our more pressing current challenges.
Bishop Museum`s Entomology Page
Images/Databases/Directories/Catelogs/Inventories/Links from the Bishop Museum`s Entomology Dept.
Biology of the Hawaiian Islands
Good info on some natives such as the Happy Face spider and the carnivorous catepillers. Be sure to check out link to Dr. Steven L. Montgomery!
Mauna Kea`s Wekiu Bug
There is a Maui species of Neseis but I couldn`t find a picture, so this is the closest image. Good explaination of the food sources and living conditions these aeolian creatures have adapted to.
USGS State Fact Sheet Info
Information about Argentinian ant problem with other good links from Hawaiian Ecosystems at Risk project.
Hawaii`s Natural Heritage Program Invertebrate List
OK, I got onto this webpage from a search on Google, but a few days later I found they are updating this portion of their site, and it should return in the future. Not many photos, but a really organized database of native invertebrates, their status, and links to the same about their specific ecosystems. Nicely done. Good luck.
Hawaii`s Natural Heritage Program
Access to databases; the orgin of the natureserve invertebrate list.
Birding Hawaii Links
Great source of Hawaii based nature links, not only about birds, from Birding Hawaii.
Volunteer Links
Links to conservation oriented volunteer opportunities on Maui. Can lead to a memorable vacation!

Most photos from the Silversword Alliance website.