Why did you bring it inside?
Did the person who sold you this bonsai tell you to do that?

That's probably why it's dying/dead. Not only do plants need air circulation,
but outdoor shade is several times brighter than the sunniest window indoors.
In other words, even in the shade, your plant would be better off outdoors.

I doubt those were mosquitos - most likely fungus gnats that eat decomposing
matter (like peat moss). Fungus gnats proliferate in moist, peaty soils, so I'll assume
your plant has been kept too wet in a soil that stays wet for too long.

No way to ID the plant without a pic.

Josh

Thanks for your reply. I have a book that says that bonsai plants are OK kept inside, as long as you keep them in a bright location... I guess I should have been more careful. I will put it outside, and also try uploading a picture...

This is my bonsai, the camera makes the leaves a lot greener than they really are.

Here is a link that might be useful: {{gwi:19335}}

To get rid of the fungus gnats you can brew up some mint tea (I've heard it works with chamomile as well) and while it's still not (not too hot) you can carefully pour it on the soil. The heat will kill the larve and the smell will drive off the flies (best to do it outdoors). I did it about a month ago and have yet to see one return. Some people do it and don't see them back for years.

Thanks for providing a pic.

Get it outside in some bright shade, not full sun. If it recovers, move it into a sunnier location.

The best way to get rid of fungus gnats is to simply get rid of the peat-based potting soil.
Plants kept in shallow bonsai containers have even greater need of a well-aerated mix because
any water that perches in the soil will dramatically reduce the volume into which roots can grow.
In other words, if the bottom half-inch of soil is saturated in a 1.5 inch container,
that means that roots have 1/3 less volume into which they can grow.

Also, fungus gnats don't really harm plants...they're mostly just a nuisance.

Josh

Was the window you were keeping it in full sun or sunny most of the day? It might have also gotten too hot. Do you recall if the nursery had the plants in a shaded section or if it was full sun? When it's shaded that usually means you could have it indoors as long as it doesn't get too much sun (morning is usually the best). I still set mine outside every so often as well, so that they can get some temperature variance and so forth.