Try leaving the top of the bin covered with an old towel.......allows lots of air circulation while keeping the flies out.

Harry

I do use the lid on mine. There are some videos on you tube on how to set the bin up. I used a smallish drill bit and put holes in the bottom of the tote for drainage. I also used a hole saw to drill some holes on the side near the top of the bin. I put screen over them. Used some adhesive to hold the screen in place. Last thing I did was put some wood blocks in a second tote and set the first one in there. Worms have been in a little less than a week and they seem to be doing well.

Yeah, what Matt said... to that I will add, using a hot-glue gun will work on most materials. All my bins (not Rubbermaid brand) have 1" holes drilled in (using a hole saw bit) and screen (porch screen material) hot-glued in place. Here is a video I made from still photos to show how I built my bins... I made it for another thread in which someone was curious but I couldn't seem to attach photos to my postings... https://youtu.be/1u9yvCkVHWk

All good suggestions, I would just like to say I rarely have any drainage, usually only when I feed melon.

Several inches of shredded paper on top will usually keep fruit flies down, as well as help buffer from excess water, and keep the bin from getting too dry. Add more whenever needed.

Does the screen on the air holes help to keep out the fruit flies and other pests? I am hoping it will. This is an indoor project for me and keeping the pests manageable is important to me

I find paper is more effective. Fruit flies are very small and so the screen has to be very tight weave. If you're worried, do both.

Will porch screen effectively keep out flying pests? I suppose it'd depend upon the screen mesh and size of the pest. I can't say for sure which it will and won't... all I can do is just relate my experiences.

In the past, during winter we'd occasionally be plagued by fungus gnats... this was due in part to using peat based potting soil mixes brought indoors from the outside. We will also at times experience fruit flies by bring home bad fruit from the store. Vinegar traps do work on controlling the fruit flies.

First winter we started with 2 worms bins in the basement... the bins were kept without lids down in the basement in a separate laundry room and everything was just fine... for awhile. Then along about near the end of that winter couple fungus gnats somehow found there way down two floors and into the laundry room in the basement and... there began to slow multiply. It kept a steady supply of gnats flying around the house until my wife finally got fed up and made me put the bins in the garage. By then it was already mid-spring and we were up to 6 worm bins... all bins had the lids on since I feared the possibility of a stray rodent slipping into the garage and feasting on my precious worms. After a short time there appeared to be no more gnats breeding in the bins that I could tell. The cold in the garage must have killed them all... that's my best guess anyway.

During the summer all the bins were moved to the backyard shed... lids on and in the shade. One bin became a breeding ground for black soldier flies... the larvae proved to be a win for our koi (free live koi food... worms AND larvae, yum). None of the other bins contained BSF larva so I'm left to assume one got in during a feeding when the lid was off 'cause they are just way too big to get through a screen mesh without leaving a giant hole in it.

This past winter was a mild one and all the bins were left in the garage with lids on all winter... by the end of winter a couple bins had huge fungus gnat populations. Like I'd lift the lid off one an a black cloud would emerge, but since they are not good fliers they immediately landed on a nearby wall and one spritz of insect spray and they all fall down dead. This scenario was repeated about once every few weeks through the spring whenever I lifted the lid off to feed the worms. I don't know how or when they got in... more curious is I don't know why the adult gnats don't leave out through the screen mesh unless they don't fit. So I'm going with, they don't fit through the screen mesh.

Fruit flies have never been a problem in the bins, indoors or outdoors... plus they are so much larger than fungus gnats the if the gnats can't get through the mesh, I sincerely doubt the fat fruit flies could either.

In conclusion: My best guess is that gnat and fruit flies don't fit through ordinary porch screen... but I can't guarantee it.

One thing that I did for aeration with my rubbermaid was to cut out the bottom leaving about a two inch lip and then cut out 1/4" hardware cloth to fit. The idea was to simulate the factory trays method of aeration in their trays.

I had a rubbermaid-style bin for years and recently moved to a can 'o worms. I knew my ventilation had been insufficient but I hadn't realized how much so! In the homemade bin the finished castings were always a muddy mess. Now they're textbook perfect.

I keep mine in the basement and don't have issues as long as I remember to add more bedding material and keep the feeding down. You can check out my video in the link.YouTube Video

Seriously fan-girling over here! I think I have watched ALL of your videos! Thanks for your reply! Since this post was made, I think I have done a pretty good job. Even expanded to a 2nd Rubbermaid along with my WF360. So I have 3 units going. Loving vermicomposting! Keep posting! I love update videos!