General Information

Habitat Requirements

The damselfly is a stream-obligate insect that inhabits one confirmed stream system on the island of Rota. This stream occurs within a forested portion of an area known as Talakhaya that contains the entirety of available stream habitat on Rota.

Food Habits

Adult damselflies are predaceous and feed on small flying insects such as midges and other flies. The immature larval life stages (naiads) of the vast majority of damselfly species are aquatic, breathe through flattened abdominal gills, and are predaceous, feeding on small aquatic invertebrates or fish (Williams 1936, p. 303).

Movement / Home Range

The damselfly is a stream-obligate insect that inhabits one confirmed stream system on the island of Rota. This stream occurs within a forested portion of an area known as Talakhaya that contains the entirety of available stream habitat on Rota. A few individuals were observed and one male & one female specimen were collected outside the Talakhaya Water Cave (also known as Sonson Water Cave) located below the Sabana plateau (Camacho et al. 1997, p. 4; Polhemus et al. 2000, pp. 1–8). The size of the population at the time of discovery was estimated to be small and limited to the stream area near the mouth of the cave. The primary source of the stream is spring water emerging at the limestone-basalt interface below the highly permeable limestone of the Sabana plateau (Polhemus et al. 2000, pp. 1–8; Keel et al. 2011, p. 1). This spring also serves as the main source of fresh water supply for the population of Rota (Polhemus et al. 2000, pp. 1–8; Keel et al. 2011, p. 1). In January 2014, 2 males were observed flying above a portion of the stream located at approximately 770 ft (235 m) in elevation, and below the Talakhaya (Sonson) Water Cave (Richardson 2014, in litt.). In November 2015, Zarones et al. (2015b, in litt.)found one individual along a stream 744 yards (680 m) to the west of Water Cave area, not connected to the stream at the Water Cave.

Reproductive Strategy

The general biology of narrow winged damselflies includes territorial males that guard areas of habitat where females will lay eggs (Moore 1983a, p. 89; Polhemus and Asquith 1996, pp. 2–7). During copulation, and often while the female lays eggs, the male grasps the female behind the head with terminal abdominal appendages to guard the female against rival males; thus males & females are frequently seen flying in tandem. The immature larval life stages (naiads) of the vast majority of damselfly species are aquatic, breathe through flattened abdominal gills, and are predaceous, feeding on small aquatic invertebrates or fish (Williams 1936, p. 303). Females lay eggs in submerged aquatic vegetation or in mats of moss or algae on submerged rocks, and hatching occurs in about 10 days (Williams 1936, pp. 303, 306, 318; Evenhuis et al. 1995, p. 18). Naiads may take up to 4 months to mature (Williams 1936, p. 309), after which they crawl out of the water onto rocks or vegetation to molt into winged adults, typically remaining close to the aquatic habitat from which they emerged. Adults have been observed in association only with the single perennial stream on Rota;therefore, we believe the larval stage of the Rota blue damselfly is aquatic.

Other

The Rota blue damselfly belongs to the family Coenagrionidae, and it is the only known damselfly species endemic to the Mariana Islands. This species was first described in 2000 (Polhemus et al. 2000, pp. 1–2) based upon specimens collected in 1996 when a few individuals were observed and one male & one female specimen were collected outside the Talakhaya Water Cave (also known as Sonson Water Cave) located below the Sabana plateau (Camacho et al. 1997, p. 4; Polhemus et al. 2000, pp. 1–8)