Dratted knats!

happyhoosierwormsJune 7, 2010

I've searched the forum and have found some comments that the knats are easily controllable but no advice on how to actually do this. I have really happy worms but am not happy about the knats. They appear to be the regular annoying ones that go after the fruit bowl when things get a little ripe. And they're big enough to see but way too fast to catch. I'll try just about anything except chemicals, spiders and lizards. :)

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Yeah I sometimes get lots of those gnat fly things especially when things warm up. You should be able to keep their numbers down by keeping any decaying material covered with a layer of coir or something. They are tenacious though and one little corner of decaying matter will allow a bunch of them to do their thing. You can try using newspaper or cardboard to cover up the scraps but they tend to work their way through that kind of layer. I have found a soil kind of material is the best. Coir, finished compost, potting soil that kind of thing. Keeping it dry might work better too rather than wetting it down. Not sure on that last point.

    Bookmark   June 7, 2010 at 6:33PM
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Apple-cider vinegar traps for fruit flies.

Yellow sticky fly paper for gnats.


    Bookmark   June 11, 2010 at 8:08PM
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I had completely forgotten about the vinegar traps! Set one out last night and TONS were in it this morning. I plan to leave the trap out for a while and watch the surface of the bin to see if I have any stragglers. Then I guess I'll have to top it off with some soil or coir. I don't really want to buy stuff for it, but the shredded paper and cardboard on top get damp enough to attract the knats. And since I run everything through a food processor the moisture level stays pretty consistent. Ah well, the cats are spoiled, the worms will be spoiled too.
Thanks for all the tips!

    Bookmark   June 12, 2010 at 1:25PM
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What has helped me was to freeze then thaw all food to kill anything and help decay. I only feed my food scraps and try to keep low moisture and lots of bedding. (dry newspaper & cardboard)

    Bookmark   June 19, 2010 at 9:55PM
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OMG!! I also am having a heck of a time keeping these darn knatts away!! Thanks for the Info!! Im going to try everyone's advice!!

    Bookmark   June 23, 2010 at 1:54PM
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Just so you know, this is taking some time and I'm not rid of them just yet. So be patient. Their numbers have decreased and I have added another tray to get the worms out of the tray I want to harvest. I change the vinegar trap every two or three days. And I plan to use some soil on top now as I can't find any coir locally that doesn't have "stuff" in it. I'm hoping the soil will finish them off. Oh and I have been keeping all the produce I eat in the fridge so that knats have can't go after that either.

    Bookmark   June 24, 2010 at 4:56AM
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Yeah I almost always keep my scraps in the freezer but I haven't noticed it really help in the long run. If there are exposed food scraps (even small bits) there will almost always be annoying flying bugs on them fairly quickly especially in warm weather. Physical barriers seem to work best for me. I recently used a bunch of layers of moist newspaper on top of a new bin and it seems to be helping quite a bit. A couple layers alone never seems to really do the trick for me.

    Bookmark   June 24, 2010 at 6:31PM
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I have covered the top of my bin with a old piece of wood. At least 3/4" thick. The worms seem to like it and it keeps the knats down too. Just be sure to keep the food scraps or other food toward the middle of the piece of wood, and perhaps covered with some of the bedding material.

    Bookmark   July 1, 2010 at 6:12PM
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Ok, I have reached a knat population of epic numbers. The vinegar traps are catching some but their numbers have clearly outweighed a trap. (and I have realized it's actually spelled gnat not knat)
This morning I have been furiously googling to try and find a solution as my bin is in my kitchen and I have to find a way to get this under control. A few dozen flying around pestering me while I feed the wee beasties is one thing. A thousand or more on my sliding glass door calls for more extreme measures.

Here are the facts:
Bin is not too wet or too dry.
All food is either kept in fridge or airtight containers.
No other bugs are seen in or around bin. None.
Food is always buried well.
Bedding is mixture of paper, cardboard, coir and coffee grounds.

Bin unfortunately has to stay inside as we've had the hottest summer in 11 years. Heat and humidity, even in the shade, is unbearable for any beast.

In reading about these pests it seems what I though was a 24 hour life span is actually a four month life span. So even after the warm temps outside cool off I may very still be doing gnat-battle.

I can sew up a pup tent for the bin out of some old curtain sheers to help. But what I'm trying to get the courage up to do is use the Gnatrol that I've used in my house plants before. If I kill off the little wee beasties I would just feel awful.

I found this other post of the forum in my googling this morning and am wondering what other opinions are. they speak of a product from Garden Safe, but Gnatrol is the same thing.

I have to do something. Looking for advice.


    Bookmark   July 31, 2010 at 8:10AM
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I've had problems with fruit flies in the past. I've taken several small bottles or cups, added a piece of very ripe banana and a small amount of water with a drop of dish detergent. Cover the opening tightly with plastic wrap, and then poke several tiny holes in the top. The flies will have a hard time getting back out through the holes.

It has worked wonders for me, but it is a bit of a hassle because the "bait" must be changed regularly. I don't know if it works for gnats, but it's worth a try.

    Bookmark   July 31, 2010 at 9:07AM
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antoniab(5 WofChicago,IL)

This is what I do when the gnats get bad.
I have a small canister vacuum cleaner, and suck the little beasts from the air.
When I go to open the bin, I have the skinny attachment on the hose, the one for vacuuming behind cushions and between the stairs. Edger, I think it is called. I have it ready, and open the lid just a crack and stick the edger attachment in, with the vac running. I don't stick it in far, just enough to suck the gnats out as I open the lid. In a second all the gnats from inside the bin have been hoovered. Then I open the bin lid all the way, and suck any strays out of the air. I will also wander around the kitchen vacuuming up gnats as I go. I like to sneak up on them on windows and around fruit in baskets and the like.
Pretty soon they are mostly gone. If I do this daily, I can keep them under control.

Oh, and empty your vac outside, well away from your kitchen. My vac has a permanent bag that you shake out. I spray the bag with bug spray each time and let it dry before using it, and most of the gnats are dead when I shake them out.

I did not think of this myself, but read it on a worm forum a while back, and goodness bless the person who thought it up! It is a godsend in the summer time!

    Bookmark   July 31, 2010 at 10:36AM
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Put that mess outside in the shade.
Stop feeding until the gnats are gone.

    Bookmark   July 31, 2010 at 1:25PM
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Thanks for the responses.

Vacuuming not an option as I have a bagless one. I used it to clean up the dead ones that fell into the slider sill and getting them out of the filter was a nightmare.

And just to clarify there isn't a huge swarm around the bin. looking at it, even when you remove the lid or move the trays you'd never know there were more than a dozen of these things in the house. They all seem to have migrated to the slider.

I've been spraying the slider with white vinegar and cleaning them up with a rag. Their numbers are decreasing. It's a pain, but I want them OUT. Upside to that, my slider is wicked clean!

I just fed the worms yesterday but will stop for a while. I think that's going to be harder on me than it will be on the worms.

I won't put them outside though. Our temps will be in the low to mid 90s all week. I don't even want to go outside, so again, mommy guilt wins. Plus, a couple of my friends are paying close attention to my trials and tribulations before they get their indoor bins going. And two of them don't have the option of putting a bin outside. So I thought I would suck it up and pretend I am a high rise city dweller instead of just a condo city dweller with a patio and find the solution that they would have to use. Not everyone lives in a house with access to a yard.

I will hold off on the Gnatrol for now.

    Bookmark   July 31, 2010 at 3:44PM
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Putting food scraps in the freezer does no good. Both the adult fruit flies and eggs can last a long time in the freezer. i'm not sure about the maggots.

    Bookmark   July 31, 2010 at 7:03PM
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My bins all happily survived 100 degree plus heat waves (5 days or more) out in the shade. Just leave the lid off and place some damp hessian or similar on top.

You can also use fly spray, apparently it doesn't bother the worms. I have used it myself.

    Bookmark   July 31, 2010 at 10:13PM
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Add food in paper bags. Like the Rx or lunch size. The number of bags in seem to equal the number of bags I need for kitchen scraps so I never buy them. Or wrap in a sheet or two of newspaper. I just lay the new offerings on top with out burying.

Since switching to flow through and mostly bagging wrapping in paper or putting material through the bin a second time which covers recent food additions my fruit fly population is down to one or two. I do not freeze or nuke. This has the advantage of self balancing the carbon.

    Bookmark   July 31, 2010 at 10:25PM
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We had to put our worm tower in our unheated basement because of the knats and little flies. THe rw survived last winter down there just fine, and I don't notice anymore annoying flies and gnats around the bin or in the house.

    Bookmark   August 3, 2010 at 1:52AM
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Geez, these little fungus gnats are awful. I, too, am dealing with a massive bloom in my worm bin (a modified jumbo Rubbermade trunk).

Tried using "Gnock-out Gnats" spray with BTI, but due to the bin's design, the bottom is now a messy swamp of worm tea. The BTI had no effect, and last time I opened the bin to feed the RWs I saw the cardboard on top was swarming with the little nasties.

Hauled the bin out into my garage until I could decide what to do: adopt stronger control measures or just dump the entire contents of the bin in the back easement and start over when the weather gets cold.

Last night I chose to install a "No Pest Strip" INSIDE the bin. I've heard that it will exterminate all of the fungus gnats over time, and will not harm the worms. When I opened the bin, I found that there were worms all over the inside, crawling up the walls and gathered on the surface of the yet-to-be harvesting castings on the unused side of the bin.

Guess it's just too wet right now. Added a bunch of dry shredded paper to help bring down the moisture inside.

My only concern is this: since I live in Central TX, and my garage is not air-conditioned (it does NOT catch the sun at the hottest time of day, so that helps), am I putting my worms at risk of overheating?

I've turned on a box fan in the garage to help move air around, and installed a cheap indoor/outdoor thermometer into the bin. This morning it read 83.5 degrees F.

Any advice or input is most appreciated!

    Bookmark   August 4, 2010 at 11:17AM
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Hi there--just joined to give a response to you, so please forgive me if I'm going over old ground anyone else has already covered. I think I've got a fairly unique setup, though, that works really well for me, and I thought I'd pass it on.
I've had worm bins outdoors in Central Texas (Austin, Dripping Springs) for several years now and love it. They are a lot tougher than folks seem to think, enduring temperature extremes (so far) of 11 F to 112° F, so I wouldn't worry too much about your shaded garage. Composting does slow during the dead of winter, but never so much that it's a problem.
After trying a few homemade tub-type designs, I came up with a design I really like: utility sinks with a sand/gravel substrate on bottom to serve as a filter, and a wood framed, hinged screen cover on top. Although I can and have harvested compost from them, the really easy solution is to turn on the hose, run water through them, and collect it in 5 gallon buckets below. Instant compost tea! And no sorting through the worms. Moisture keeps them cool; they survived that horrendous summer of '08 when we had over 60 consecutive days of 100+ degree heat. Since they are freely draining, though, there's never a problem of too much moisture. The sand filter at the bottom serves a couple of functions: it stays moist for a long time, which maintains a constant beneficial microbial population, and it serves as a mechanical filter to keep the worms and the humus in the bins. I just water them when I want to water my plants. They also do just fine on their own without any attention when we bail on the heat and head somewhere else for a couple of weeks.
I throw an old polyester bedspread/comforter across them for the winter, and I did add a string of Christmas lights below the bins for those 11° nights, but that's as much coddling as they get. They probably would have survived without it, but I like 'em, and I didn't want them to suffer unnecessarily :). They (I have 2 bins, and recently started a 3rd) are under the eave of a screened porch, where they get some rain, depending on the direction of the wind. I use bagged hardwood mulch for the bedding, and scratch out a hole with a little hand cultivator, dump in the compost, and cover it back up. I had a passing problem with gnats several years ago when I was just starting the first bin. I read that since they breed at the surface, cover it, so I placed an old folded rag towel on top, below the screen, which I would just pull back when I added compost, then replace. It did the trick. It eventually rotted through, but I've not had to replace it. I don't know, but I suspect there's just enough other life in there to outcompete them. The longer I have them, the more trouble-free they see to become.
Hope some of this was helpful, and that you enjoy experimenting with them!

    Bookmark   August 7, 2010 at 9:37PM
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"I think I've got a fairly unique setup."

Austin, We've Got a fairly Weird setup. :-)

You harvest the castings by running water through them, and collect it in 5 gallon buckets? You are the second poster on the board using this method. The rest of us will be thinking about you guys while we are playing in our mud and worms. Yinz is starting a new harvesting religion.

I'm a wee bit deaf.

Did you say you live in Dripping Sinks?

    Bookmark   August 8, 2010 at 3:19AM
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I had read about a Water Harvest Method in 'The Worm Book' by Nancarrow and Taylor, but had been unable to find anyone who actually did it. So these worms are flushed with 4-5 gallons of well water (as opposed to city water) to harvest the castings? How often do you do this? With hard wood chips as bedding, you are not shredding paper or cardboard and burning up paper shredders either. With a wire screen at the drain to keep the sand in, these drain continuously into a bucket.
3 questions, please-
How thick a layer of sand?
How often do you feed and how much?
I tried a tote with 4" of cardboard and 2 pounds of EFs but I was flushing every 2 days and the water would stink awful. I gave it up but have recently started again. This time I flush with fresh water and only weekly, so it is going better.
I really like the simplicity of your system and hands free harvesting is awesome! This may be the best worm composting system ever. And all of it can be bought at a home improvement store (except the worms).

    Bookmark   August 8, 2010 at 8:20AM
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I recently bought sand for my pool filter at Home Depot(less than $6 a bag). Even an inch in the bottom of a tote would require a pretty sturdy frame to hold it off the ground.

But that much sand would probably require not much more than window screen supported by a piece of hardware cloth over the outlet. A threaded coupler and a hole saw would be all you would need.

    Bookmark   August 8, 2010 at 9:39AM
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antoniab(5 WofChicago,IL)

It does sound perfect! And my city gives away woodchips, free for hauling, so the bedding would be simple to come by too.

Hubby will be thrilled at a new project...

    Bookmark   August 8, 2010 at 12:33PM
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Dripping sinks, eh? clever, thanks for the laugh :)

I've found that the amount of water used doesn't make too much difference. We built our current home, and for the landscaping, I started a couple hundred native plants from seed and cared for them from anywhere from 6 months to 2 years before they were put in the ground. (They were planted mostly in a mix of vermicompost and granite sand when I had enough compost to go around; otherwise I bought some local potting soil. They did great!) During that time, I watered each bin at least 5 gallons at a time 2 or 3 times a week; sometimes 15 gallons at a time. Now, they generally only get watered 3-5 gallons every 2 or 3 weeks, as I just don't need the tea. They seem to be happy either way. The volume of compost in the bins is what is most affected by it. When I was watering so often, I rarely had/got to harvest compost. I could add scraps and mulch, but the bins never got too full. Now I have to pull compost out at least once or twice a year so I have enough room for more input. I generally add an overly full 1.5 gallon bucket of scraps twice a week. I water the bins first, then add the scraps, so that the water is run over finished compost.

I had a 55 gal. rain barrel in town, and used rainwater when I could. When I ran out, I used city water. The worms didn't seem to mind, but I could really see a difference in the plants. (Now our whole house is on a rainwater system, which all of us, plants, people, and worms alike, love.) My sisters in town have both begun using the same system with city water, and haven't had any issues.

An interesting note (to me, anyway) was that at one point when we were living in town, the water in the plastic rain barrel went septic. The screen on top of the barrel was loose enough to allow some mosquitos to enter and lay eggs, but didn't allow the ensuing offspring to escape. So a lot of dead mosquitoes turned the water septic, and it smelled awful. I ran it though a bin anyway, and it came out smelling much better than it went in. Emptying the barrel and adding some gravel to the bottom created a habitat for beneficial microorganisms, and solved the problem. I never could get a satisfactory seal on the screen that came with the barrel.

I bought the sinks at a Home Depot for $14. They've since tripled in price, unfortunately. They're pretty sturdy, and they have to be--the bins are extremely heavy. A good footing underneath them is important. I like the height, though--no bending over to compost. The idea is a modification on a composting system by Anna Edey of Solviva; she set up a toilet composting system that uses a flush toilet in the house, and runs the effluent through a worm bin outside the house. Genius idea, in my opinion. I'm hoping to try a similar setup one day, which is why I wanted to experiment with the sand filter. Sand filtration is a great cleaning system for black water, and I thought adding one to her design would provide an additional safety factor. I wanted to get some experience with it before messing around with potential pathogens. Still haven't worked up the courage to set that toilet system up, but one of these days I will!

The sand system in the bins is: screen over the drain hole, a mound of gravel around that to help hold back the sand, then about 4" of sand on the bottom of the sinks, covered with dampened hardwood mulch and worms. The sand was bagged and marketed for kids' sand boxes; the gravel was also a bagged landscaping product. I think some of the swimming pool filter sand has diatomaceous earth added, so I steered away from that. A tiny bit of sand will move through the system, so I guess over the years the sand is depleted. I haven't figured out a way around that.

I used paper scraps for a while, but didn't really like the way that worked. The mulch is a local product, recycled tree trimmings, so I'm fine with that, and I just recycle our used papers. The mulch is shredded; perhaps a bit more finely than what I imagine you might be referring to when you say wood chips. It's soft to the touch, not chunky, and easy to grab by the handful. I keep a galvanized trash can full of it next to the bins, with a little plant saucer in it to serve as a scoop. I buy 2 or 3 $3.00 bags of it a year. We've also bought it in bulk for garden beds and set some aside; in this hot climate, it's extremely helpful to keep moisture from evaporating.

I think the screens on top are an important aspect, too. I noticed a couple of people referring to lids on their bins. I started that way, and had real difficulty managing the temperature. It's just too dang hot around here. One disaster resulted in worm soup, and kept me out of the world of worms for a couple of years. Poor things.

I'm running on again; as you can probably tell, I really like this set up. I've had some experience fending off fire ants and soldier flies, but I think I'm starting to go overboard. I'll ramble on some more if anyone wants to know, but perhaps it should be another thread? Seems like I got a bit off the topic of gnats :) Thanks for the interest, hope some of it helps.

    Bookmark   August 8, 2010 at 1:22PM
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eaglesgarden(6b - se PA)


Please start a new topic about this set up and be sure to include as many pictures as possible of the setup during as many phases of construction as possible! I'm sure that I am not alone in saying that this set-up has been fascinating to read about, and I am thinking of starting one of my own. The more information you can offer, the better.

I'd also like to hear about your ventures with ants and flies.


    Bookmark   August 8, 2010 at 1:41PM
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cathy centex- Thanks for answering my questions about you worm system. I have a 4x3x2 deep box that is sealed inside with fiberglass. Now it is sitting on saw bucks, but I could make a frame and put steel legs under it to handle the extra weight. I heat this in the winter with a red rope light down in the VC. If the rope light was buried in the sand, it would have the same effect (increased microbe activity and thus worms feeding and busy). And with a drain in the bottom, I could do the tea harvest you are describing. I would be using my existing worm box with modifications which would save me some cash. You do not state how many worms you have per utility sink. I am also interested in the BSFL cure but we do not have fire ants in NC that I am aware of. Thank you for this information.

    Bookmark   August 8, 2010 at 7:29PM
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steamyb, sounds like a great set up, and a nice size. the bigger mass probably keeps the temperature swings to a minimum, and I'll bet it looks better than plastic sinks. I've always wanted to disguise those behind some sort of cabinet or screen, but not enough to get it done, apparently.
as to how many worms I have...how about we say multitudes? I know somebody has a calculator out there, but I haven't looked at it. As many as the system will support, and when there gets to be too many, they migrate on rainy nights. I've seen evidence of their departures on autumn mornings; I can't say about any other time of year. This of course makes me very glad they're outside. And also makes me wonder if anyone might know where red worms originated? I saw one account that said southern US, another England. I read about a worm scientist in Oklahoma who said there were native ones that would do the same job, but can't really say from whence mine hail. Other than the bait shop. I started with 3 pint containers, probably about 36 worms. The bins are teeming with them now.

eaglesgarden, thanks for the kind words and positive feedback. I went searching in the files for some photos, and have a few of the completed bins, but none taken during set up. I'll have to look around a bit for instructions on how to post them; this is the first forum I've participated in, and I don't know much about how things work. For that matter, I'll have to explore before I know how to start a new topic, too! Total newbie. But I'll do my best to post it somewhere.

    Bookmark   August 11, 2010 at 2:32PM
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eaglesgarden(6b - se PA)


Starting a new topic is easy. At the top of the forum you want to post it in (in this case, vermicomposting) there should be a link to "Post a Message". This will start a whole new thread, with whatever title you want... If i could suggest "outdoor kitchen tub sink vermicompost system". :^)

You'll have to do some independent research regarding the picture posting...I've never tried to do that myself! Although, I do know that it is easier if you have a flickr account or something like that.

    Bookmark   August 11, 2010 at 10:19PM
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Hello All,

I would like to thank the post that suggested rubbing alcohol. YEAHHHHHH �������� it worked. I sprayed the knats as they flew around and down they went. They were also in the sink I sprayed it and they just curled up. I also sprayed around the plants and it seemed to keep them off.

You can also try covering you soil with rocks or gravel I did that today it was suggested to me today by an individual at Home depot.

Thanks again,

Happy growing ��

    Bookmark   July 9, 2011 at 11:20PM
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Heres what I did. Last year when I started my worm bin in april I got some gnats quite a few. My bin is inside and firstly you should always cover your bins with shredded damp paper to discourage gnats as they will be attracted to any moist soil. Using that idea I ordered some yellow sticky cards. I filled some pots of moist soil and stuck some stick cards in this soil. Ok the sticky cards will only capture the flying adult gnats , so what about the eggs they lay. I got some bonide insect granuals and put some in the moist soil per directions for the size of pot. Done correctly the eggs laid will not hatch and yellow cards capture the adults. Within a few days you will notice gnats on the cards and eventually maybe a week no more gnats. I placed the pots near the worm bins as deterance as they are already attracted to the moist bins. I also use the bonide granuals in seedling soil or cuttings as soon as I spot any gnats buzzing the area. This worked so well for me I had no gnats inside all winter as in the past. Good luck if you have this problem. I suggest not to use this product within 2 mo of putting outside for nectaring insects and hummingbirds.

    Bookmark   February 18, 2014 at 2:46PM
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My gnat solution: my worm bins are former recycling bins. Air holes are covered in screen, and I throw a towel on top. Freeze food for at least a day before adding. I never found that burying the food under bedding did a darn bit of good. The gnats will find it. I actually stopped burying it bc the worms feed from below. They seem to like this better than burying. NO gnats.
-PC in DC

    Bookmark   February 19, 2014 at 9:07PM
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