Black gnat

I have a big problem w/ little black gnat's on my indoor and greenhouse plants. I have been spraying them daily w/ a Hydrogen Peroxide mixture and it seems to help, but it is starting to hurt the plants. If I don't spray everyday at the strength I am using it does nothing at all to the gnats. I have tried a couple of sprays from HD and Lowe's, but I don't want to introduce to many pesticides since these are enclosed areas and I don't want to spend 20 bucks on a small bottle of anything either.

Here is a pic of the eggs they are laying on the spinach. I have been wiping them off almost daily, but it is getting to be too much work. My plants inside are not as bad as this, but if I don't do something soon I am sure they will be.
Any help would be appreciated.

Except for the eggs on the leaves I would suspect fungus gnats--they fit your description but I think they lay their eggs in the soil. If it is fungus gnats, I usually only have trouble with them when I'm keeping things a little too wet so you might try letting the plants dry out more in between waterings. The gnats themselves don't hurt the plants, but the larvae in the soil can chew on roots but since they're usually only around if you're keeping things a bit too wet, the overwatering will probably do more damage to the plant than the gnats will. Try buying some mosquito dunks or a product called Gnatrol and add those to the water the next time the plants need to be watered. They both contain Bt which will take care of the larvae. Insecticidal soap ought to get rid of the adults or you can put up yellow sticky traps if you don't want to spray more things on the plants.

Thanks, I did not know what color traps to make, but I will give that a shot. I let everything dry between watering for the most part. I did notice that they stay away from the seedlings that are in peat/vermiculite mix. The flies not only spend time in the soil, but they also like to sit on the underside of the leaves. I wish they would stay sill long enough for me to take a picture of them.

What do you think the eggs are from? I have not seen anything other than a soldier beetle in the gh (that is where the eggs are showing up)
Thanks for the help.

The little spots do not look like insect eggs of any kind; I suspect that they could be residual salts or sugars after evaporation of water droplets exuded by the plant.

Thanks for the info. I went ahead and through out the "infected" plants and started some more. I finally got the gnat problem under control. As for the "eggs", I will keep an eye out to see if that comes back when the plants start to grow. More than likely they were not eggs since I had nothing on any of the other plants and have yet to see any bugs (except the gnats). Thanks for the help.