Dragonfly or Damselfly nymphs are a danger to your tank.
They will eat lots of stuff if allowed to stay. They can eat small stuff shrimp and fry. Bad news for an aquarium or fish tub, or pond with small fish for that matter.
Often plants are purchased and sometimes they can come in from plants grown outside or in green houses.
I will now probably have nightmares after seeing these things eat from YT vids.
New to FW fish? First tank in a long time or EVER??? Need some info on keeping fish?
Start here - Aquarium Advice Article
FW Favorites right now Clown Loaches, any shrimp - SW Vase Red Mangroves