Megalagrion xanthomelas

The body length of dragonflies is from 33 to 37 mm. Wingspan from 35 to 40 mm. Males are black with red spots on the chest, the first three and last three segments of the abdomen, Females are yellowish brown, the first segments of the abdomen are black ^[3] . The length of the adult larva is from 18 to 20 mm. At the tip of the abdomen are three long thickened gills. The egg is elongated yellowish, its pointed end is darkened. The length of the egg is about 1 mm ^[4] .

They are found on the islands of Oahu , Molokai , Lanai , Maui and Hawaii ^[1] . Previously inhabited the island of Kauai ^[3] . They are confined to low-lying areas, but individual individuals can be found at an altitude of up to 1000 m above sea level ^[4] .

Larvae develop in stagnant water bodies, with a water temperature of 21 to 31 ° C. and acidity from 6.6 to 9.2 ^[5] . Females usually lay their eggs in the petiole stem of the fern Marsilea villosa or the stem of Commelina diffusa. Less often, eggs are laid in water, while the female lowers most of the abdomen into the water, and the male holds her by the breast with anal appendages. Larvae feed on the larvae of long-winged dipterans ^[4] . At the beginning of the 20th century, the species was one of the common and widespread species in the Hawaiian Islands. Since the beginning of the 1940s, the number has decreased, and by the 1990s it has decreased to a critical level ^[5] . The abundance of this species was probably influenced by the introduction of alien fish species G ambusia affinis and Poecilia latipinna into the water bodies, which were introduced in the Hawaiian islands to combat mosquitoes ^{[6] [7]} . Factors that have a negative effect include the use of water for irrigation and the introduction of the semi-aquatic plant Brachiaria mutica , which forms dense thickets and areas with open water disappear in its places of growth. It is included in the IUCN Red List of Threatened Species with the status VU ( Vulnerable Species ) ^[8] .