A large number of federally endangered dragonflies that were raised in captivity at a South Dakota lab for over the period of past five years will be released into the wild this week.

The dragonflies were raised at the University of South Dakota (USD) after eggs were collected from a dragonfly in southwestern Wisconsin.

Project head Daniel Soluk, a USD professor said in a statement that their recent decision of releasing dragonflies into wild aims to preserve the species, which was listed as endangered by the federal officials in 1995. The species can now be found in Illinois, Michigan, Missouri and Wisconsin.

Scientists since long thought that the species has gone extinct. But the belief changed when an adult specimen was found in 1988 in the Des Plaines River Valley, southwest of Chicago and was later identified as a Hine's emerald dragonfly. The Hine's emerald dragonfly was first discovered in Ohio

So far this week, Soluk has released three out of 20 possible dragonflies at a forest preserve. Scientists hope that these federally endangered dragonflies will be a good match with the small population in the wild.

Soluk said, "We are trying to maximize their survivorship in captivity. Not very many dragonfly eggs survive to become adults in wild, and bringing them into the lab can dramatically increase their chances".

According to experts, female dragonflies lay eggs by dropping tip of their body into shallow water, and immature dragonflies known as nymphs hatch from eggs in the spring.

Nymphs live in water for about four years, until they crawl out, shed their skin for last time and emerge as flying adults. The adults live only four to five weeks between June and August.