cover the fruit scraps with bedding.

The presence of Fruit Flies can mean there is too much food too close to the surface. Add more, dryer, bedding material to the surface and be sure further additions of fruit waste are buried deeper.
The larva of the Fruit Fly need a food source, moisture, the right temperture range, and enough air to hatch and then grow into the adult flies. Eliminate any one of those and there will be no Fruit Flies.

But this is a worm bin. I don't know if you can cover it up and add more browns, because heat is bad for worms. Worm bins are only cold composting. Worms won't eat the fruit flies or eggs because that is not in their nature. I have never done I worm bin. I got rid of fruit flies by microwaving my fruit to kill eggs and making sure there are no holes that the flies can go in, but I heard adding browns works, but that would cook the worms LOL

Adding some browns will not hurt. Burying the stuff deeper will help with the fruit fly problems. If it were to start heating, the worms would burrow into a cooler spot.

I am not the micro-managing type so I add scraps to the bin and just ignore the fruit flies. They die off when it gets colder.

Microwaving the material you put into your vermicompost bin will kill off the eggs that the fruit flies have laid on the skin as well as the bacteria that would aid in digesting that material. The relatively high moisture levels of a vermicomposting operation should help keep temperatures down to levels comfortable for the worms in those bins.

But, the bin is filled with bacteria over all, so pre mircowaving the fruits does not hurt the bacteria count. That is the silliest thing I ever heard of. There are like millions of bacteria in any rotting bin.

Worm bins are problematic because and (I just thought of this)if there is a bottom and they can't move out of the bin and it gets too hot or too acid or too something they can't leave, they die. If there is no bottom and they don't like it they leave and more away, hence no worm bin anymore.

I have never had a worm bin either, which is why I am not going to attempt to give advice on how to operate one. :-D

Just would not want to burn up the worms trying to kill the fruit fly eggs. It's better not to let the eggs go in the bin. Did you know most bananas from the store come with pre-laid fruit fly eggs in the peels? I did a lot of research on fruit flies after years of having them like crazy in the summer.

They're part of the game. I must keep my worms indoors because of temperature extremes. My worm box contains two four x four wire mesh screens in either side of a rubbermaid tub. Eventually, I had to place that black cloth type of stuff.. I guess it is landscaping cloth over thosee air vents To keep the fruitflies down in the house and allow my poor little wormies to have something other than ground oatmeal and rabbit pellets. For a long time I couldn't put waste in there because of the fruit flies. The landscape cloth did not eliminate the fruitflies (cuz they were already present) but it sure does keep them down to a non-noticable level.

Another trick: process all forms of worm food. If you're feeding it waste grind the waste in the blender. This causes the food to break down more quickly creating less time for other critters to make a home especially if you have a larger worm population of voracious eaters. Remember, worms don't eat food - mostly. They eat the bacteria it turns into. Essentially, they eat "crud" and all forms of this "crud" is what other critters enjoy. In addition to a Lean diet, this helps keep the box clean but ti's not optimal if you want your worm population to expand at any reasonable rate.

Or you can just feed them a lean diet of ground rabbit pellets and oatmeal (combined with water to make a paste) adding a touch of molasses and a touch of ground eggshells for further nutrients and feed your worms this lean diet to help eliminate other critters.

Wormies thrive better on a diet conducive to other critters so if you can put the buggers outside and leave them be that is best to increase population. They'll love you more for it. They don't care about gnats. Gnats provide a mutually inclusive eco system where everything thrives and enriches the soil.

bon

Also, invest in a coffee or herb grinder - a coffee grinder is tougher. Utilize this grinder to break down dried eggshells and rabbit pellets. I cannot emphasize the use of molasses sufficiently. Molasses deters bad bacteria but allows good bacterial to thrive. If good bacteria is present molasses allows those microbes to explode. If you're not already utilizing molasses I recommend it. Be sure to purchase nonsulphured types. You'll watch your wormies go crazy over it. The egg shells do something 0 I'm not sure what but I've noticed it stimulate their reproduction and I think they use it to help digest foods (like bird utilize gravel in the gullets).

Whatever changes are being made to a worm bin always do it with "just a touch" noticing their reaction (good or bad) and proceed accordingly always giving the worms a chance to escape whatever you're adding lest it not agree with them. As long as we don't do anything to kill the worms in mass they'll survive!

bon

I wonder if I should put some molasses in my compost bin to make more bacteria grow? I heard that sugars are plant growth inhibitors.

Sugars a plant inhibitor? Plants love sugar. I'm not sure of possible toxic effects if super high quantity is applied. But molasses is an amazing plant food!