Rare damselflies released on O‘ahu

  • Courtesy of the state Department of Land and Natural Resources

    The orange-black damselfly is a vulnerable population at the risk of extinction. It’s one of about 25 species of endemic damselflies found only in Hawai‘i.

HONOLULU — A new group of orange-black damselflies has just been released into the wild on O‘ahu, adding numbers to a species on the edge of extinction.

It’s one of about 25 species of endemic damselflies found only in Hawai‘i, is very rare, and is the subject of reintroduction efforts by a team from the state Department of Land and Natural Resources Division of Forestry and Wildlife and the U.S. Army.

Eleven of the 25 recorded endemic damselfly species have been found on Kaua‘i at some point, and of those 11, some are becoming increasingly difficult to spot.

The orange-black damselfly has gone extinct on Kaua‘i and Lana‘i. The orange-black Hawaiian damselfly is found in small populations on Hawai‘i Island, Maui and Moloka‘i.

“They used to be on Kaua‘i, but haven’t been for a long time,” said William Haines of the state’s invertebrate program. “There aren’t even any specimens around anymore, just written reports of seeing them.”

On O‘ahu there is only one wild population of the 2-inch-long, native damselfly, tucked in among the buildings of the Tripler Army Medical Center’s vast campus. Not exactly the ideal place to improve the lot of this species.

“It’s not a super stable place for orange-black damselflies,” explained Kapua Kawelo, the U.S. Army’s natural resources program manager on O‘ahu.

In the early 1990s the Army teamed up with the University of Hawai‘i to try and establish a second population of the insect at Dillingham by moving damselflies from Tripler, but that effort was not successful.

More recently, the DLNR DOFAW invertebrate program joined with the Army to raise the endangered damselfly in a breeding facility for introduction at Dillingham. With the development of new captive-rearing techniques for the species, they can release much higher numbers.

“So far we’ve released about 4,000 damselflies reared in captivity,” said Haines. “We’re seeing the first evidence of wild reproduction at one of our release sites.”

How do they know? All the released damselflies have a small number marked on their wings. Haines added, “We’re starting to see individuals emerging from the stream that are not marked, which means they are wild-born. That’s really encouraging to see they’re completing their entire life cycles in the wild.”

In June, after a full year of weekly releases, the team will stop releasing damselflies and continue monitoring the success of the program, hoping for a sustainable population at Dillingham. Both Kawelo and Haines are optimistic.

“The final test will be when we pull the plug on continual introductions from the lab,” Kawelo commented.

Past efforts show the need to step back and evaluate the program, the reason being that the species was imported to the islands to control an invasive species, but it ended up backfiring.

Their biggest predatory threat is the mosquito fish, introduced in the early 1900s to control mosquitoes. The fish feed on the immature, aquatic stage of the damselfly as well.

Haines said, “Very quickly you saw damselfly populations declining after the introduction of the mosquito fish.”

Native damselflies play a role in the environment, providing ecosystem services. The adult damselflies prey on other flying insects, like non-native mosquitoes and flies. The immatures are also predators, eating aquatic insects like mosquito larvae.

Each release of the orange-black damselfly involves 50 to 120 of the delicate insects. After they leave their netted enclosures, they fly off to hunt insects in the surrounding forest. Eventually, they will return to the stream to mate and lay eggs in aquatic plants.

“If we can sustain a population at Dillingham for an entire year, that is encouraging for the success of long-term populations, not only on O‘ahu, but also on other islands,” Haines said.

Kaua‘i is home to many different species of damselflies because of the abundant water on the island, which provides breeding and feeding grounds for the insects.

“Look at the Blue Hole on Kaua‘i,” Haines said. “Species are breeding in the seeping water from the waterfalls.”

Haines pointed out that not all damselfly species have to breed in standing water — a quality unique to the species endemic to Hawai‘i. Some lay their eggs in the base of tropical plants, which are moist but don’t contain standing water.

“Things seem to become so isolated on Hawai‘i that they diverge and do their own thing,” Haines said.

On O‘ahu, Haines calls the future of the orange-black damselfly dire. “Even though there are populations on other islands, the Tripler population is the single wild population left on O‘ahu, and we don’t want those genetics to disappear.”

That is why there is a race against the extinction clock.

Kawelo concluded, “This species is one of the first I began working on more than 25 years ago. The orange-black Hawaiian damselfly was not endangered at that point, yet despite all the challenges finding a predator-free site, I’m really optimistic.”

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Jessica Else, editor, can be reached at 245-0457 or jelse@thegardenisland.com.

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