Beautiful Demoiselle (Calopteryx virgo, bg: Sinyo romolniche) is a type of dragonfly from the family Calopterygidae. It posses over the typical for the order pivoting head, large faceted eyes, two pairs of veined wings and a long body. Sexual dimorphism is observed among this species, meaning both sexes differ in appearance. Males have a dark blue body with metallic luster, the wings are almost entirely dark brown with blue luster. Females have a metallic green-brown body and their wings are pigmented almost entirely in smoky brown, partly translucent.
Adults commonly sit on parts of plants sticking out above the water in illuminated areas. Sometimes the species can be observed in clusters of dozens individuals. In the period of puberty the adult insect (imago) can make up to 600-700 m away from the ponds. Representatives of the species have been found near the forest areas and tree belts. Beautiful Demoiselle eats flying insects captured in flight.
The life cycle of Beautiful Demoiselle occurs with incomplete transformation (incomplete metamorphosis). Females of the species most often lay their eggs on the underwater stems of coastal fouling built by representatives of the family Cyperacaea (sedges) or on the leaves of water-buttercups. From the egg hatches a larva with large eyes and massive long body. It lives at the bottom of the water basin or between the water plants. Just like the adult insects, the larvae of Calopteryx virgo are carnivorous. They eat almost anything that moves. Once they have reached a certain maturity, the dragonfly nymph (larvae at late stage of development) comes out of the water, usually in the morning. The change of stage is called hatching. After leaving the water, the larvae wait to dry. After several hours, the skin on the back splits and the head appears first, followed by the body and legs. Then the insect rests for few hours until the wings are dry and the adult dragonfly is ready to fly.
The species is widespread in Europe, including Bulgaria. It is found throughout the country, particularly around small fast-flowing rivers in woodlands. It inhabits the upper reaches of the rivers at an altitude of 400-500m. This trend doesn't apply in the further south-eastern regions of the country. In the regions of Strandzha Mountain and Eastern Rhodopes the species is common in areas with altitudes between 0 and 400 meters. Another peculiarity in the distribution of Beautiful Demoiselle is that the earliest (26.04.1994) and the latest (04.09.1997) reported meeting with the species are also from South Bulgaria. Perhaps regional studies from these parts of the country will prove the extended distribution period over the entire spring-summer season; while in other regions of the country the species is common only during the summer time.