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Attracting black soldier flies

Black soldier flies are probably the least domesticated of the invertebrates we work with on our farm.  Unlike managing a worm bin, when managing black soldier flies you have to be aware that your insects spend part of their life cycle outside the bin, so you need to find a way to attract these wild critters to lay their eggs in your rotting food scraps.  This task has two parts --- producing just the right scent and then providing optimal egg-laying habitat.

Black soldier fly adults don't eat, but they know that their offspring are going to be hungry, so the females are drawn to the odor of rotting food.  If you live out in the boondocks like we do, you can probably just throw some food scraps in your bin at the right time of year and wait for the noxious smell to attract momma flies.  But if you're putting your black soldier fly bin outside your back door and live in an urban setting, you might want to try out one of the attractants shown to bring in black soldier flies without also attracting complaining neighbors.  Dried corn soaked in water so that it ferments is supposed to be a good attractant, as is sour milk.  If you have a friend who's already running a black soldier fly bin, you can ask for some of his compost tea and paint the liquid on the inside of the lid  of your own bin --- black soldier flies are attracted to the scent of other black soldier flies.

Black soldier fly eggs in cardboardUnlike house flies, black soldier flies won't lay their eggs directly into the rotting food, so you also have to give the mother fly a spot to lay her eggs.  In a pinch, she'll lay her eggs on the inside walls of the bin, but it's better to make her a cardboard egg-laying station.  Just cut small strips of corrugated cardboard and attach them to the inside of the lid of the bin so that lots of crevases are exposed.  Momma fly will lay her eggs inside the cardboard corrugations, and when they hatch, the larvae will drop down into the rotting food below.

Using these tips, you should get black soldier flies coming to your long as you're trying at the right time of year.  Adults fly only during warm weather, with April being the earliest you're likely to see any and with the majority coming out later in the summer.  So if you build your bin now, you'll want to wait to bait it until you're getting ready to plant your summer garden.  Or you can jump the gun and buy some larvae, but be aware that the larvae won't turn into adults until warm weather, so their population won't expand in your bin the way worms would.  I'm not sure it's worth it to buy black soldier fly larvae unless you live in an area where they aren't found in the wild and are hoping to jumpstart a wild population.

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This post is part of our Black Soldier Fly lunchtime series.  Read all of the entries:

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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Black Soldier Flies really like coffee grounds. I get them free at Starbucks. I always start saving household scraps when the weather is getting into the 60's. I put a good amount of coffee grounds in my bin and then I start putting the scraps on top of the coffee grounds and that way the food is on top and will start to stink for the flies to find it. Rotting meat works good too!!! If you lightly nail up some pieces of corregated cardboard either at the edges or above the scraps and such, you will have more larvae. My box is wooden with a piece of plywood for a lid to control moisture, heat, and light. Without pieces of cardboard, I still have more bsfl than I can feed. If our household scraps slow down, I supplement with some coffee grounds or roadkill, but with roadkill unless it is fresh, it always has regular fly larvae on it and I have to wait for the ones that hatch to cycle out of the bin. No biggie. Hopefully the weather is up to about 75 by this time. You will go through all kinds of insects and household flies while waiting on BSFL and then they always catch me by surprise. Just when I am wondering when it is going to take off, the food scraps start to move and that is the indicator that bsfl are getting big enough to start working the bin and then their ferimones (I think) run most all other insects out. Any regular fly larvae that is laid on the food pile will be consumed by your bsfl. The only thing about coffee grounds is they retain heat. This is good in the spring, cooler weather, or if you feel you want to warm up your bin some (seems to stimulate them and probably speeds up their life cycle) but in the summer and with a lid on your box, tote, bucket, etc., too many coffee grounds will generate too much heat and I have heard that the larvae will die at 113 degrees farenheit. I don't use a thermometer although I have in the beginning. I had a kill off one time due to too much heat and moisture and limited evacuation. When it gets too warm, you will see the larvae piling up in the corners and along the edges.
Most areas of the country have bsf and all you have to do is start off with some stinky stuff. Dead fish work good, but later if you want to run your hand through the bin, you will get stuck by the fine bones as they do not eat some things like bones, teeth, fangs, hoofs, hair, cloth, grass, leaves, wood, glass, metal, plastic, eye membranes, tomatoe skin, avocado peels, orange peels, apple cores and stems, and more I can't think of right now, but all the light weight things will come to the surface and I just pick them out and throw them on the ground for the chickens. My box is split in half, one half being the regular bin and the other half has some dry material with a lid on it (again to control moisture and light but with some evacuation spots)and this end is for some of the larvae to pupate into bsf and the other end goes up to a pvc pipe and to the ground for my chickens. I know I have talked about a lot more than just attracting flies but I hope someone will be able to learn from my 4 or 5 years of experience with them. It is fun and I enjoy it and I don't buy very much chicken feed anymore. Wenesday July 30th 2014. God bless you. BM

Comment by cybpmp2 Thu Jul 31 08:44:06 2014

I have read some articles here and I have been having this project of starting a poultry using every cycle of energy, conservating energy through waste and my lead work to actualizing my project is the black soldier fly. cybpmp2 I read your article ..

Comment by Godfrey Wed Aug 21 05:28:09 2019

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