What are these little green flying bugs

I have a 50 gallon freshwater tank. Recently I noticed on the surface of the water little green bugs that like to fly out when I open the lids. When cleaning the tank I also saw them in tiny worm form on the rocks I use for building caves and stuff. Now I think they are gone, but I would still like to know what they were.

Hmmmm - interesting. I know it is more alarming for you than anything, but in my research for you this evening on this - I came up with little to no information.

The bugs may actually be Gnats that are being attracted to the condensation under your aquarium hood and often algae and spilled fish foods reside there as well. The gnats are probably feeding on that, and whenever you open the lid of the tank, some probably land or fall into the water and desperately try to get out by jumping and flopping around. Then again they may be something totally different from gnats and may have been introduced via the addition of a live plant/rock, or one that is an aquatic insect and somehow got into the house.

As for the worms or larvae, what you MIGHT be seeing is Planaria. These are harmless, tiny little white worms that usually are present in the aquarium at all times but hide in the gravel and come out either at night or anytime if there is a high concentration of food in the water. Aquariums containing oscars or other large, meat-eating fish almost always have a worm or two at all times squirming around. The way to control Planaria is careful feedings and many water changes. There are some species of fish that are known to eat these tiny worms as well.