Dragonflies and Damselflies of The Cook Islands

The Cook Islands (Te Kūki ʻĀirani or ʻAvaiki Nui) is a group of 15 islands spread across 2,200,000km² of the South Pacific Ocean. Each island is unique and diverse in habitat, flora, and fauna, though unfortunately the true extent of biodiversity is unknown. We're lucky to have some Cook Islands dragonflies and damselflies from Atiu and Rarotonga collected in the 21st century. In this blog for ‘Epetoma ō te reo Māori Kūki ‘Āirani (Cook Islands Language Week) we take a closer look at the specimens in our collection and what they can teach researchers about the ecology and evolution of these special creatures.

Blog by Melissa Kirk, R T Shannon Assistant Curator of Entomology

The Cook Islands (Te Kūki ʻĀirani or ʻAvaiki Nui) is a group of 15 islands spread across 2,200,000 km² of the South Pacific Ocean. The 15 islands are divided into two separate groups: the Northern Cook Islands and the Southern Cook Islands. The Northern group is made up of seven small islands: Pukapuka (Te Ulu o te Watu) Rakahanga (Tapuahua), Tongareva (Māngarongaro), Manihiki (Te Whūinga o Nīva), Nassau (Te Nuku o Ngālewu), Palmerston (Avarau) and Suwarrow. The Southern group is made up of eight islands: 'Ātiu (ʻEnuamanu), Aitutaki (Araura), Rarotonga (Tumu-te-varovaro), Mangaia (Aʻuaʻu), Maʻuke (ʻAkatokamanava), Mitiʻāro (Nukuroa), Takutea (ʻEnuaiti), Manuae (Te Au o Tū).

Each island is unique and diverse in habitat, flora, and fauna. Unfortunately, the biodiversity of The Cook Islands is not well studied and insect diversity is unknown in Western research. While some work has been conducted on the economically important species or pest species, little focus has been given to indigenous fauna. A small amount of Western research has been conducted on dragonflies and damselflies (Odonata) of The Cook Islands. In 1911 the first record of Odonata on The Cook Islands was documented by RIS, but, the specimen, Diplacodes bipunctata from Rarotonga (Tumu-te-varovaro) was collected in 1860s. The research done on Odonata from The Cook Islands is limited, another record by RIS was made in 1913, a record in 1949 and a survey in 1953 by Lieftnick, Walker and Deitz in 1979 recorded Odonata species present, a list of records of specimens from Wise in 1980s, and a record in 1997 and a list of records from Martens in 2010. However, in recent years the Cook Islands Database have been describing and documenting species present.

A handful of specimens have been collected from these Islands by entomologists, with some within Auckland Museum collections. In the 1930s, amateur entomologist Charles Edwin Clarke collected in Rarotonga (Tumu-te-varovaro), where he collected numerous types of insects, dragonflies included. In 1969, Keith Wise the previous Curator of Entomology at Auckland Museum collected specimens of dragonflies and damselflies from Atiu ('Enuamanu) and Rarotonga (Tumu-te-varovaro).

Within the Auckland Museum entomology collection are some magnificent, beautiful and eye capturing dragonflies and damselflies from The Cook Islands, collected by Charles Edwin Clarke and Keith Wise.

_{Pantala flavescens (male) (AMNZ136410) collected by Keith Wise in 1969 from Ngatangiia, Rarotonga (Tumu-te-varovaro).}

There are many traditional names for dragonfly within The Cook Islands including Karakara‘avai (Rarotonga), ‘Iva (Mangaia), Kākaravāia (Ma‘uke, Miti‘āro), Pākiriāvai (Aitutaki), Pepe Īkolo (Pukapuka). Makiuti Tongia, tumu kōrero (knowledge holder) in Rarotonga explained the role of dragonflies:

"Good for keeping the namu (mosquito) population down. I welcome it inside the house before a heavy rain. [I] allow it to fly around in the house as one of our tiaki for incoming rain warning by 2 days’ time average. Beautiful insect and tiaki for our family, [a] guardian angel."

-Personal communication with Liam Kokaua, 22 July 2023.

Ancestors of dragonflies and damselflies date back to the Late Carboniferous Epoch. They are aquatic or semi-aquatic as juveniles and are often indicator species of habitat quality and even species richness within ecosystems, due to their sensitivity to habitat quality and environmental changes. Dragonflies are the most successful predator in the world, with hunting success rates as high as 97%, they feed on smaller insects like mosquitoes and sometimes small fish. Dragonflies’ high success rates of predation is due to the evolution of their wings for flight and adaptations of their eyes.

_{Hemicordulia sp. (AMNZ85944) collected by Keith Wise in 1969 from Atiu (ʻEnuamanu).}

Pantala flavescens

Pantala flavescens is a dragonfly within the Libellulidae family, it is also known as the Wandering Glider. It is believed to be the most widely distributed dragonfly in the world. The Wandering Glider is a large dragonfly 4.5cm in length and has a wingspan of between 7.2 to 8.4cm. The head is a reddish to yellow colour, the thorax and abdomen is a golden yellow or sometimes an olive brown colour. Males have a reddish wash in the abdomen, and a brown patch at the border of each wing.

Pantala flavescens are native to The Cook Islands, they occur in both the Southern and Northern Cook Islands groups and are considered very common. They inhabit freshwater habitats in mountainous areas and are common in open areas. Interestingly, this species was the first dragonfly to re-establish in Bikini Atoll post-nuclear testing. It is also the only dragonfly species found on Easter Island which contains individuals with dark wings. They are powerful flyers; they have the farthest known migration of any insect, with individuals flying between 14,000 to 18,000 km. Genetic analysis indicates that these dragonflies are flying large ranges thus making gene flow widespread, creating a world gene pool. They have also been found in the Himalayas at 6,200m, and are therefore the highest-flying dragonfly in the world.

_{Pantala flavescens (male) (AMNZ136410) collected by Keith Wise in 1969 from Ngatangiia, Rarotonga (Tumu-te-varovaro).}

Due to their aquatic life stages, dragonflies are vulnerable to climate change, thus the raising temperature will likely impact the distribution of this global species. Liao et al. (2023) have modelled the future distribution of Pantala flavescens under climate change models. This research found that both the type of habitat will change, and the amount of suitable habitat will change. With increasing global temperatures, the range tolerance for this species expands across the equator, and their distribution can extend into higher elevations.

Museum collections are a unique opportunity for researchers to track changes to species as they adapt to changing environmental pressures. For example, the Pantala flavescens in our collection is from 1969, which means scientists might be able to determine how much the species distribution or phenology may have changed in the 54 years since it was collected.

_{Pantala flavescens (male), in flight, in a paddy field. By Basile Morin - Own work, CC BY-SA 4.0,}

Diplacodes bipunctata

Diplacodes bipunctata is also known as the Small Red-body Dragonfly, within the Libellulidae family. It has a wide distribution, occurring in several islands of the south-pacific, Australia and in New Zealand. Within New Zealand this species occurs at the top of the North Island, mostly in Northland, but has been recorded as far as Fiordland. This species is native to The Cook Islands, they occur in both the Southern and Northern Cook Islands groups and are considered very common. They are early colonizers and inhabit freshwater, swamps and pools and are found in lowlands to mid-uplands (200m) areas within The Cook Islands. Diplacodes bipunctata have a wingspan of around 5.5cm. Sexes of this species are sexually dimorphic, meaning males and females appear different, males are red in colour, whereas females are yellow.

_{Top: Diplacodes bipunctata (male) (AMNZ136427) collected by Keith Wise in 1969 from Takuvaine Valley, Rarotonga (Tumu-te-varovaro).}

_{Bottom: Diplacodes bipunctata (female) (AMNZ136430) collected by Keith Wise in 1969 from Takuvaine Valley, Rarotonga (Tumu-te-varovaro).}

Anax guttatus

Anax guttatus is a dragonfly in the family Aeshnidae, it is also known as the Blue Waist Dragonfly. Anax guttatus occurs across the world in Africa, China, Malaysia, India, Japan, Australia, Pacific islands and many more. This species is native to The Cook Islands, they occur in Southern and Cook Islands groups but are considered rare, their presence in Northern Cook Islands groups is unknown. This species inhabits standing or slow-moving waters such as ponds, and can occur in forest ecosystems or urban areas. It’s a large dragonfly around 8cm long, with a wingspan of 11cm. This species has a brown abdomen with blue/green markings down the side, a green thorax and blue/green eyes and head. Females and males are similar, however for females the brown patch on the inner side of their hindwings is pale or absent. Anax guttatus is known to mate-guard females, which is when males guard their females after mating to stop them from mating with other males. This ensures that her offspring carry his genetic material. This species is an indicator species, signifying the health of riparian ecosystems in Karnataka, India.

_{Anax guttatus (AMNZ136402) Museum specimen collected by C.E. Clarke in 1934 from Rarotonga (Tumu-te-varovaro).}

Tholymis tillarga

Tholymis tillarga, is a dragonfly in the family Libellulidae, it is also known as the Coral-tailed Cloudwing or Blue-flash Dragonfly. This species is a migratory species known to be widespread across Africa, Australia, Asia, and Pacific Islands. It is native to The Cook Islands, they occur in Southern and Cook Islands and are considered widespread. This species inhabits standing water bodies including lakes, ponds, and swamps. Tholymis tillarga has red eyes, thorax, and abdomen in males, and brown in females, the hindwing has an orange patch. Males have a white opalescent patch next to the orange patch on their hindwings. They have a body length of around 3cm and a wingspan of between 3.3-3.7cm. Tholymis tillarga also exhibit mate guarding of females by males.

_{Tholymis tillarga (AMNZ136477) collected by C. E. Clarke from Rarotonga (Tumu-te-varovaro).}

Tramea transmarina

Tramea transmarina is a dragonfly in the Libellulidae family, also known as the Mountain Dragonfly. This species is found in Australia, Fiji, Southeast Asia, and Pacific Islands. It is native to The Cook Islands, they occur in the Southern Islands but are considered rare, it is unknown if they occur in the Northern Cook Islands. They inhabit lowland and mountainous areas around freshwater. They have red eyes, a dark thorax and abdomen, with males brighter than the females. This species also has unique markings a large brown patch on the bases of the hindwings.

_{Tramea transmarina (AMNZ136491) collected by C. E. Clarke from Rarotonga (Tumu-te-varovaro).}

The Damselflies

Damselflies are Odanta, the same order as dragonflies in animal species classification. However, damselflies are in the suborder Zygoptera and dragonflies are in the infraorder Anisoptera. There are several different characteristics between dragonflies and damselflies, including the shape of wings and their position of their wings at rest. Dragonflies hold their wings flat over their body at rest, whereas damselflies hold their wings up at rest. Additionally, dragonfly and damselflies eyes are different. Dragonflies have eyes that connect on the top of their head, whereas damselflies have widespread eyes that do not connect.

_{Differences between dragonfly and damselfly eyes. Dragonflies’ eyes (top) connect at the top of their head, while damselflies' are wide apart (bottom).}

Ischnura aurora

Ischnura aurora is a damselfly in the family Coenagrionidae, it is also known as Blue-tip Damselfly, ‘Iva (in Mangaia) or Piongi (in Pukapuka). This species has been recorded throughout Pacific Islands, Australia, Norfolk, Lord howe and Kermadec Islands and as occasionally New Zealand. In The Cook Islands this species occurs in Southern Cook Islands groups and is common, it is unknown if it occurs in the Northern Cook Islands groups. This damselfly is very small, it is less then >30mm. They inhabit marshes, rivers, swamps, and ponds. Females and males are slightly different in appearance, males have a red abdomen with a blue and black tip whereas females do not. A very similar species Ischnura rubilio occurs in India and Iran, it was once thought to be the same species as Ischnura aurora.

_{Ischnura aurora aurora (AMNZ136501) collected by Keith Wise from Rarotonga (Tumu-te-varovaro).}

Acknowledgements

I would like to acknowledge Liam Kokaua and Olivia Taouma, for their help with the traditional names of dragonflies and damselflies, and the ancestral names of Islands of The Cook Islands. I would also like to thank Liam for his communication with Makiuti Tongia, tumu kōrero (knowledge holder) on the role of dragonflies/damselflies in Rarotonga (Tumu-te-varovaro).

Liam Kokaua is Project Curator Mātauranga Māori at Tāmaki Paenga Hira Auckland War Memorial Museum.

Olivia Taouma is Pule Le Vā, and part of the Pacific Development team at Auckland War Memorial Museum.

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