Can I guarantee that you won’t get sick from contact with black soldier flies?

There is no species of animal on Earth that could live up to that guarantee, but researchers agree that black soldier flies (Hermetia illucens) are not disease carrying pests like common filth flies.

handful of black soldier fly larvae

Black soldier flies are different

I can understand people’s revulsion at the thought of flies in general. The common house fly is associated with 277 disease organisms. On the other hand, BSF have been the subject of many scientific studies and they are not known to be transmitters of disease-causing pathogens. I’ve read dozens of articles about using the larvae to process manure and about feeding them to animals and I’ve never come across any warnings about handling BSF. It’s easier to find information about humans transmitting pathogens than about BSF doing so. You can, however, find some nice photos of researchers holding big handfuls of BSF grubs and smiling broadly (the researchers that is). There are several aspects of the BSF life cycle that result in their non-pest status.

black soldier fly blog logo

All flies emerge relatively clean

The process of pupation results in all flies emerging relatively free of pathogens. It’s the lifestyle of the adult flies after that point that makes the difference.

BSF adults (winged stage) only live for a few days as opposed to 30 or more days for house flies. Because of their short lifespan adult BSF don’t need to eat and in fact don’t even have working mouth parts. For that reason they rarely enter human habitats and they don’t compete with humans for food. House flies must eat so they cycle back and forth between waste material and our food. It’s that cycle that results in the transfer of pathogens and it’s the absence of that behavior that keeps BSF relatively clean.

After emerging, the adult BSF mate and the female flies away in search of a suitable food source to lay her eggs near. The female’s preferred site for depositing her eggs is close to, butusually not on the food source. Eggs laid on the food source will have a higher chance of being inadvertently consumed by already feeding larvae. This is another characteristic that contributes to the BSF status as a non-pest species.

Unlike many other flies, BSF adults do not go into houses, they do not have functional mouth parts, they do not eat waste, they do not come into contact with waste, they do not regurgitate on human food, and consequently, they are not associated in any way with the transmission of disease. They do not bite, bother or pester humans in any way. – Dr. Paul Olivier


The amazing digestive system of BSF larvae

In contrast to spreading disease there is evidence that the presence of BSF larvae can reduce pathogens in waste material.

Bacteriological interactions associated with manure digestion by maggots are favorable. Maggots are competitors with bacteria for nutrients and often reduce bacterial numbers greatly, or eliminated them altogether (Beard and Sands, 1973; Sherman, 2000). Maggots may consume and digest microorganisms, and produce antibacterial and/or fungicidal compounds (Landi, 1960; Hoffmann and Hetru, 1992; Levashina et al., 1995 and Landon et al., 1997). As maggots reduce pathogens in manure they may make it safer for organic vegetable production.

From the same article:

Flies that have been used experimentally to process manure include house flies (Musca domestica), face flies (Musca autumnalis), blow flies (usually Sarcophaga sp.) and the black soldier fly (Hermetia illucens). Except for the black soldier fly (Furman et al. 1959), all of these are considered pests as adults due to their disease vector potential, behavior and preferred habitats.

Preliminary studies with black soldier fly larvae indicated a reduction of pathogens in an artificial medium or manure innoculated with larvae. Numerous studies using dried, rendered and fresh maggots as animal feed have revealed no health problems resulting from this practice. Preliminary bacterial culturing of self-collected soldier fly prepupae from a recent swine trial revealed no pathogens


BSF grubs lessen or eliminate the breeding of pest flies

When a food source has an established colony of BSF larvae other species of flies are rare or even absent. The larvae produce an info-chemical that alerts other flies to the fact that the source of food is already being dominated by BSF larvae.

Common sense about working with black soldier fly larvae

I’m not suggesting that black soldier flies or their larvae are perfectly sterile. You and I are not perfectly sterile. Pathogens are everywhere and it is common sense to wash your hands after working with BSF, just as you would after petting a dog or shopping at the grocery store.

Update: Since we now have a discussion forum we will be disabling comments here on the blog. Anyone can read the forum, but to join in on the conversation you will need to register. This is an easy and painless process, and it’s necessary to keep spammers from, well, spamming up the place. :)

The forum can be accessed here (forum) and you will see a link for registration in the upper left corner of the forum. The legal language on the registration form is very basic and is what came with the forum software. In short, we won’t share your information, and please don’t be vulgar or break the law. 😉

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75 thoughts on “Black soldier flies are not vectors of human pathogens

  • June 19, 2008 at 9:26 pm

    Very interesting article here! :) I haven’t yet read the source material so will still need to look them up, but have to say the larvae look more like woodlice in your picture!

  • June 20, 2008 at 7:14 am

    Hi Mosey, thanks for visiting! The BSF larvae do resemble woodlice in a photo, only the BSF are MUCH prettier. :)

  • June 25, 2008 at 2:15 pm

    I found BSFL in my compost last year and looked them up online and the info I found on them made me happy. They are impressive little critters.
    So far this year they haven’t made an appearance in my compost. I think it’s because I haven’t been stopping by the coffee shop and getting grounds like I did last year. It seems they really like that stuff.
    Glad to see your blog. I think these critters are awesome.

  • June 25, 2008 at 8:52 pm

    Hi Dirk.

    I’ve noticed the same thing about BSF and coffee grounds. Could they be caffeine junkies? One theory I have is that the grounds help them digest food more efficiently because of the caffeine, the texture, or both.

    I’m glad you found my blog and I hope you’ll let us know if any BSF larvae show up in your compost.

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  • August 20, 2008 at 11:22 pm

    BSF larva are also known as ‘Phoenix Worms’ and are excellent feed for insectivores such as Reptiles, Birds, Tropical Fish, and Sugar Gliders. They are High in calcium (about 50x +/- more then other feeder insects) and lower in fat. They also make extraordinary composter insects that can consume large quantities of food including meat and dairy before it even rots.

  • September 27, 2008 at 10:27 am

    I’m in Maryland. Had to go to metal trash can composters, as there is a rat problem here. Noticed maggots in the compost this summer. But how do I know whether they are the disease carrying houseflies or black soldier flies? Thanks.

  • September 27, 2008 at 2:21 pm

    Hi simone,

    House fly maggots are smaller than that of black soldier flies. A BSF larvae can reach almost an inch in length.

    You can also observe the area where the maggots are located to see what type of fly is present. If you see more than 3 or 4 house flies around the pile then the larvae are probably not BSF. If you see no, or few houseflies around the pile I would suspect you have a BSF colony because BSF larvae give off an info-chemical that repels other species of flies.

    If you really want to be certain about the species the best way is to put a few maggots in a jar and see what develops. If you provide them with food, water, and air you will soon have an adult fly to identify. House flies develop much quicker than BSF so if you have them you’ll know within a few days.

  • September 29, 2008 at 10:10 pm

    Me and my daughter found tons of these bad boys when stirring the compost today, we immediately recognized them as larvae, thought fly species likely, and found our way to here from searching “big larvae in compost” then searching the genus and species viola! Not many flies found in compost have such large larvae- a handy characteristic for identification. They actually look much less dingy when you bathe one in water. less brown, more yellow. We especially like their pointy heads (my son, daughter, and I) This blog is excellent, we’re going to slap the one we bathed under the dissecting scope to get a closer look. I can email my drawings if they’re any good and you are interested. I am a lab instructor for an ecology class at the University of Oregon. Me and my children study insects for fun. Thanks for a great blog, good info can be hard to find.

  • September 29, 2008 at 11:12 pm

    Jarrett, thanks for the kind words, I’m glad you had a good experience with the BSF larvae. I was laughing at myself today because I was cleaning up on of the three larvae I’ve been photographing daily. You can see that thread here. One of them had a piece of food that didn’t wash off and I had a tissue rolled up and I was gently wiping it clean.

    I would love to see the results of your examination.


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  • December 9, 2008 at 1:35 am

    Zoonotic Parasites?

    Like many pet owners I have a pet poop problem my BSFs LUUUUUV poop and have taken over the bin I used to deposit them in. The resulting compost I have dropped on the landscaping trees and not much else because I’m conserned about the possibility of zoonotic parasites.

    Has anyone studied this as a transmission vector?

  • December 15, 2008 at 8:49 pm

    Hi Pego, sorry it took me so long to respond!

    I don’t believe there is reason to worry about using the compost for growing vegetables. I’ll check back when I have some sources to share.



  • December 16, 2008 at 2:42 am

    I am very interested. I am ina pet service industry and find myself giving the Toxocariasis lecture to people who hqave the perfectly normal idea of walking barefoot in the grass that has had pet traffic. I would so love to see some research and show it to some of my clients and friends.

  • April 7, 2009 at 6:42 am

    oHHh… i thought they are pest.
    i found many of them on my backyard just suddenly and i wonder where do they came from?

    hoping for your respond!

    thank you!

  • April 7, 2009 at 8:19 am

    Hi JuwANna,

    Black soldier flies are native to the southeastern U.S. but they have spread around the world, mostly in the tropics and subtropics. They thrive anywhere that the climate is warm and humid. They can be cultured almost anywhere, but they would not survive in the wild unless the conditions were favorable.

    Thanks for commenting!

  • April 8, 2009 at 2:46 am

    i’m from the philippines in mindanao
    and i can’t seem to figure it out where did they came from. it just sudden that they appeared on nights. do they actually live on trees?

  • April 8, 2009 at 7:37 am

    juwANna, the black soldier flies have most likely been present on your property for years but they went unnoticed. The adult flies only live for a few days and aren’t attracted to people. I live where the BSF originated and they are very common, but most people here could not recognize an adult BSF. Many people here have seen the larva though, because they live longer and stay in one place, assuming the food supply is consistent.

    The adult flies are attracted to bushes after emerging and there they mate. After that the males are rarely seen and females seek out rotting food so they can lay their eggs by a good food source. After mating and laying eggs the short life of the BSF adult is over.

    Most of the people in my area know about BSF larvae because they are excellent for fishing bait. Once people use them they tend to seek out the larvae for this reason.

  • April 22, 2009 at 12:36 am

    I’m from Davao, Philippines. I’m happy to tell you that after searching the net for BSF infos, I finally made myself a bin where we throw our kitchen wastes including pig manure and chicken dung from our nearby farm. The results are great! Not only do we reduce our garbage (only non-biodegradable materials were thrown as garbage) but we also have lots of larvae to feed our chickens and flowerhorns. The rest / part of the wastes goes to my methane digester where we use it as fuel for cooking. I am currently planning to put the BSFL poop to my nearby vermi project.. Your blog is of great help. Thanks!

    That’s great Bong, I’m glad you enjoyed the blog!

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  • May 23, 2009 at 4:21 am

    Hi I posted a link to your blog this week because I have discovered BSF larvae in the compost pile I happily started when I moved to Hong Kong just a few months ago. I was immeasurably relieved to find out these guys are actually good and maybe even great for my compost pile. Now if only I can convince my kids & neighbors… :) Thanks loads for your great info.

  • June 1, 2009 at 8:27 am

    Hi Jerry, I hope I can use your blog to send a message to a countrymate regarding BSF. Really desperate to find some for our Farm, thanks!

    Hi Bong (from Davao, Philippines), this is Regina. I am based in Quezon City. Can I buy a few pieces of your BSF larvae? I would like to cultivate BSF for our farm to get rid of the houseflies. Please email jemerc(at) if you are ok to sell. Thanks.

    No problem Regina. I edited your email address so that spambots couldn’t grab it. :)


  • June 9, 2009 at 8:56 pm

    Hi, we have a worm factory that we keep in our basement and I found that we have many of these BSF’s now, Is there a way to get rid of them? How could I get them out and stay out, they are flying all around my basement. My kids love to take the worm farm into school for show and tell, I can’t have these guys flying all around the school. I see they like coffee, I’ll stop giving the worms coffee.

  • June 9, 2009 at 9:09 pm

    Hi Joyce,

    If the worm farm stays indoors you shouldn’t have much trouble excluding any additional BSF grubs. For them to occur in your worms you either have to introduce BSF eggs or allow access to females that have mated. It’s not likely you brought eggs inside unless someone collected food scraps that have been outdoors. Mating isn’t likely indoors either, especially since you’re probably getting rid of the adults quickly.

    To collect the light colored (juvenile) grubs you might try using this technique. It works even better if you find an opaque disc that fits inside because the grubs like to be under something. The “lid” should sit right on top of whatever you use as an attractant. I use moistened fish food usually, but coffee grounds, fruit, oatmeal, moistened bread, etc. will work well also. The dark mature grubs don’t eat so you can’t bait them with food. If you set the worm farm over some type of straight-walled container you can catch these grubs as they migrate away from the food in search of a pupation site. The container needs to be dry so the grubs can’t climb up the sides. The walls of the container only need to be a few inches high if they’re dry. In this photo you can see mature BSF grubs that couldn’t escape from a plastic lid because it was dry: Photo

    These bugs are beneficial and harmless so if you can manage to collect them and release them outdoors you’ll be doing a good deed. :)

    If you need clarification about anything please let me know.

    Good luck.

  • June 13, 2009 at 8:48 pm

    Hi Jerry, Bong, Regina, I am based in Pasig, Philippines. Just bumped this blog today in search of cheap food for my free range chicken in Zambales. Great Blog indeed! Saw a few larvae last month in my coffee ground – carabao dung mix for my ANC wormbed and I thought they were pests so I discarded them. Had I known earlier, would have collected them. Anyways, will be wiser next time.
    Just two questions for now: #1. How can one increase the colony of worms when mature BSF only mate outdoors? #2. Can I make an enclosure, say made of net, and simulate their natural environment with the purpose of a continuous system? Thanks very much Jerry for starting this blog.

  • June 13, 2009 at 9:20 pm

    Hi armand,

    I appreciate the nice feedback.

    1. If you keep your food source in an area that the wild BSF can access they will come to it continually and lay eggs. The main limiting factor is temperature, but I don’t think that’s an issue where you are. The best scenario is to have the BSF unit outdoors but under some type of cover that keeps rain out and fully shades it all day to avoid overheating. You can increase the size of the colony by increasing the surface area of the unit and the amount of food/waste deposited.

    2. Yes, you can enclose the colony in a net, but I don’t see the benefit of it. Adult BSF females are strongly attracted to an actively feeding colony of BSF grubs so keeping them contained in an enclosure isn’t necessary for a continuous system.

    Please let me know if you have other questions.

  • June 24, 2009 at 12:06 pm

    Hi, Thanks for the blog, lots of useful information and I’m now a bit more reassured about the hundreds of grubs wriggling away in my balcony compost.
    However, despite all the good they are probably doing to my compost and the fact that we now have no flies buzzing around it, I’m a bit concerned about what will happen next. the compost is on my balcony so I’m worried that we are soon going to be infested my the adult flys or that my compost will always be full of the grubs – there isn’t actually any of my compost that doesn’t have grubs, so I can’t use it to fertilise or repot plants.
    Any advice on how to remove them or reduce their proliferation would be helpful otherwise I fear I’m going to have to throw out all of my compost.

  • June 25, 2009 at 9:11 am

    Hi Steve,

    First let’s address your being infested with black soldier flies. I’ve raised and released tens of thousands of BSF grubs on my property over the past few years and I’ve never seen more than about a dozen of the adult BSF at any one time. In addition please consider that I’m always involved in trying to attract them. The reason they’re relatively rarely seen compared to other fly species is that their life cycle is different. Adult houseflies live for up to 30 days and during that time they need to eat of course. BSF adults only live for 5 – 8 days and they don’t eat during that period. They’re sole purpose as adults is to mate and lay eggs. When a BSF adult is attracted to any type of waste it’s almost certainly a female looking for a place to lay her eggs. For that reason the male half of the BSF population is almost never seen at all. Then, after laying her eggs the adult female BSF has no interest in the food source so she simply leaves and shortly dies. That’s the long version of “you won’t get an infestation of adult BSF”.

    I’m glad that you’ve observed how BSF repel houseflies and other pest flies. That’s something I’ve addressed many times, but it’s nice to have confirmation of that from a third party.

    You certainly can use the compose for repotting plants. If you separate a portion of the compost from the main pile the BSF will soon cycle out of it assuming you don’t add more food scraps to it. The BSF grubs are there for one reason, food. If the compost is in an open container the grubs will simply leave after any remaining food is consumed. If you want to have more control in removing the grubs from the compost you can use food scraps as bait and capture them using the method I describe here.

    You also have the option of repotting any outdoor plants without removing the BSF. As I stated above they will simply leave when there is a shortage of food scraps. You might damage some of the grubs by handling them that way, but that’s the only downside I see.

    The following post might be helpful if you haven’t already read it:

    Whatever you do please don’t throw out your compost, the BSF are harmless and the compost will have only been improved by their work.

    Please let me know if you need further advice.

  • July 9, 2009 at 6:48 am

    We have been experiencing a drought here in Houston, Tx. after several years of heavy to moderate rain during the summer months.
    The other day we got a phone call concerning leaches going into the alumni building. This was the first time I have in countered these larva and used my resources here in our Biology Dept. (nice part of working with brilliant students who are down to earth, no pun intended.)

    What I find interesting is they were crawling into the building and all over the back porch and this was after a rainfall. It’s hard to convince the women in the building these little critters are very good for us and our small environment here when they can’t stand the heron which nest at this time of the year and as we know birds poop about every 15 to 20 minutes and this isn’t the most pleasant of smells.

    Do you think the heron will eat the larva? Everything has an enemy.

  • July 10, 2009 at 2:23 pm

    Hi nancy,

    It sounds like you had several larvae in the building which is a bit odd. I’m guessing that there was some relatively old garbage near some type of opening in the building. I’m pretty sure BSF larvae don’t target indoor environments, I would guess that they more or less pick a direction and keep going until they find a suitable pupation site. If there was a colony close to the building that would explain the presence of several larvae. If the colony is/was far from the building I highly doubt you would have seen more than one or two larvae inside.

    The reason I say the garbage must have been old is because BSF take much longer to develop than houseflies. The eggs take over 4 days to hatch and then it takes at least a few weeks more before the larvae reach their full size. If what you saw were the dark colored mature grubs then those eggs would probably have been laid a month or more in the past. If you want to stop the larvae from wandering into the building I would look for the forgotten garbage that they’ve inhabited.

    I expect the herons would eat the larvae with gusto. BSF larvae are eaten by a wide variety of animals including fish, birds, reptiles, and amphibians.

  • July 18, 2009 at 8:30 am

    despite my girlfiend not liking the fact that we have hundreds of squirming larvae on our balcony I’ve kept the compost, grubs and all. It really is amazing how quickly they get through the veg waste I put in. In order to stop proliferation I tried sealing off the compost using black plastic bin liners. This doesn’t seem to have had the slightest effect on their population.
    I have a drip tray under the compost which fills up every so often with the large mature grubs. I’ve tried starving them and they seem to be (almost) indestructable.
    I have now given up on being nasty to them and have decided just to let them be and let them help me make great compost.
    Thanks for the advice on obtaining grub free compost, Jerry. If, when I need to use my compost, it’s still grub infested, I’ll use your technique.
    Thanks again for the blog and the info. These critters really are quite something.

  • July 18, 2009 at 8:45 am

    Thanks for the update Steve. I think you’ve been bitten by the BSF bug. (No, BSF don’t bite) :)

    BSF love to lay their eggs in the folds of plastic can liners so you’ve really just done them a favor. Whatever you cover the compost with the BSF will simply lay eggs on the outside of it and the tiny hatchlings (1mm X a thread’s thickness) snif out your garbage and crawl inside. BSF want one thing, decomposing food. If you ever decided to discourage them simply limit your composting to grasses, leaves and other high cellulose items which BSF can’t digest.

    Trying to starve the mature grubs is kind of funny because they don’t eat in that stage, they don’t even have a mouth. 😀 All they want to do is to pupate and emerge as adults for a few days to mate and lay eggs.

    Please let us know how the story develops.

  • July 25, 2009 at 1:11 pm

    Great blog! I am interested in using BSF in a remote third world location to compost human waste. Do you know if there is any problem using the mature BSF grubs to feed chickens that will be used for eggs and human consumption? I am thinking that using urine seperating out houses with self harvesting system (directly to the chicken yard) will solve two problems, one is that I won’t have to construct a conventional septic system and the other is that I have a feed source for my chickens. I intend to use these critters in other parts of our ecological system which includes aquaponics, worms, rabitts, etc. Any suggestions would be greatly appreciated. Richard…

  • July 25, 2009 at 2:31 pm

    Hi Richard,

    Thanks for the nice comments.

    I’m not an expert, but don’t believe there is a problem with using BSF to process human (mammalian) waste and then feeding the resulting grubs to fowl, even if the chickens and eggs are in turn consumed by humans. Of course you should get a more informed opinion before doing it.

    The idea you present is almost exactly what Dr. Paul Olivier, the inventor of the BioPod, has tried to accomplish in Brazil and also in Vietnam. Unfortunately I think he has encountered several difficulties because many people in developing countries want to emulate the US and other modern people. Maybe this “primitive” but elegant technology needs to be embraced in the West before it can be accepted elsewhere.

    You might enjoy this presentation that was put together by Dr. Olivier and others: You’ll see a reference to a urine diverting toilet at the bottom.

  • July 28, 2009 at 9:21 am

    Hi Jerry,

    I would like to see the actual work done as far as analysis of larvae and nutritional components. I’ve seen what I think is a lot of inaccurate info regarding this in the past. I have read such things as 40 % protein and the occasional 50%? Also fat levels seem to be all over the place and certainly feeding just Soldier fly larvae to insect feeding animals is not a good thing with fat levels so high.If you either have the info someplace else that I can see or can refer me to a place where accurate analysis has been done I would much appreciate it.

  • July 28, 2009 at 9:36 am

    Hi don,

    Most of the data that I’ve seen referenced is based on studies by Dr. Craig Sheppard and Dr. G. Larry Newton, who have both studied BSF extensively.

    Dried black soldier fly (Hermetia illucens) prepupae contain 42% protein and 35% fat (Newton et al. 1977). Live prepupae are 44% dm and are easily dried for long term storage. As a component of a complete diet they have been found to support good growth of chicks (Hale 1973), swine (Newton 1977), rainbow trout (St-Hilaire et al. 2007)) and catfish (Newton et al. 2004). Peer reviewed studies show that prepupae meal can replace at least 25% of the fish meal in a diet with no reduction in gain or feed conversion ratio (FCR) in rainbow trout (St-Hilaire et al. 2007) or channel catfish (Newton et al. 2004). Separation of the prepupae fat and protein would allow for formulation of more balanced diets and produce a meal with over 60% protein. Removal of the chitin would further enhance the protein content and enhance digestibility as well as produce another valuable product. Blind taste tests with tilapia and channel catfish fed diets containing Hermetia larvae indicated no significant difference between those diets and commercial diets (Bondari & Sheppard. 1981).

    Omega-3 fatty acids were enhanced in Hermetia prepupae that were fed fish offal mixed with manure (St-Hilaire et al. 2007). Omega-3 fatty acids increased from negligible levels to approximately 3%. This finding raises the possibility of enhancing other nutritional factors in Hermetia prepupae by custom feeding of the growing larvae.


    Of course the concentration of fats and protein will be significantly less in fresh larvae. I haven’t seen any studies that recommend a diet consisting of BSF exclusively and I wouldn’t think it’s a good practice to feed any animal such a restricted diet long term.

    I’m sorry I couldn’t provide more information. Perhaps you would share the conflicting reports that you’ve found so that I could follow up on this.

  • August 11, 2009 at 1:20 pm

    Hi GW, I am visiting the different sights and learning all the while. Last night in the dark with my light on (my set up is on the porch) I saw a different fly that looked like a cross between a wasp, bsf, and a yellowjacket. All he was doing besides ignoring me, was checking all the small vent holes out….almost looked like it was eating maybe larvae from around the holes? Any answers?

  • August 11, 2009 at 1:49 pm

    Bill, it certainly could have been eating larvae or maybe BSF eggs. Most BSF eggs get laid in clusters in protected crannies but I also see some being randomly scattered around the walls of my BioPod. The holes in your unit could very well have individual eggs around them.

  • August 17, 2009 at 2:47 pm

    quick question. How do you eventually separate the dirt from the soldier fly larvae? I have a good population of larvae and would like to use the dirt they are making.

  • August 17, 2009 at 7:49 pm

    Hello erik,

    If you separate a portion of the compost from the main pile the BSF will soon cycle out of it assuming you don’t add more food scraps to it. The BSF grubs are there for one reason, food. If the compost is in an open container the grubs will simply leave after any remaining food is consumed. If you want to have more control in removing the grubs from the compost you can use food scraps as bait and capture them using the method I describe here.

  • March 29, 2010 at 12:35 pm

    Hi Bong (from Davao, Philippines). Can I also buy some of your BSF larvae. I would like to start them here in Iloilo City, but I can’t find them.

    • March 29, 2010 at 2:41 pm

      Hi Jojo,

      I removed your email address from your comment because I believe it can result in your getting spam.

      Unfortunately it’s not possible for me to ship animals out of the country, but luckily it should be very easy to find them in your area where the climate is ideal for BSF. Look for larvae where people keep livestock like pigs and chickens; the larvae will be in the manure. Also they will be found in worm bins and traditional compost piles where people are processing food scraps. If you find BSF larvae in a medium like manure or compost try to bring some of that medium home with you. The combination of larvae and medium will be a powerful attractant to female BSF looking for egg laying sites.

  • March 29, 2010 at 12:51 pm

    hi jerry, do you have contact number of the people from the philippines who culture bsf? i am interested to buy from them,iam from mindanao,philippines.thanks! Nonon

    • March 29, 2010 at 2:44 pm

      Hello Nonon,

      I’m sorry I do not know anyone working with BSF in the Philippines. As I said to Jojo; it should be easy to find them in your area. Good luck!

  • May 29, 2010 at 4:18 am

    I have a lot of BSF larvae in my composting bin. They’re working very hard everyday eating any organic thing i put on the bin. I just knew from your blog that this larvae have a lot of benefit. No wonder the small lizard like to walk around the bin.

  • June 11, 2010 at 1:44 pm

    Our compost bin is in the backyard behind our house and it is abundant with larva/grubs? & they do a great job. However, we find some small ones dead on our basement floor during the period when they are active. Recently, I found 3 adult flies buzzing around my tv room. Not pleasant. You indicate they don’t go in to the house however I guess they do on occasion. How best to keep them outside and not in our house where they might find a source for laying eggs? In Atlanta, GA.

    • June 11, 2010 at 8:30 pm

      Hi Holly,

      I’ll bet the BSF larvae in your basement aren’t dead but are pupating instead. That would explain the adults in your TV room. Don’t get me wrong; BSF do sometimes go into houses but it’s unintentional because they don’t eat and only target rotting food and manure for egg laying sites. If a BSF does find itself in a house it will immediately try to escape. The kind thing to do is to gently catch it in a cup and release it outdoors. If you’re concerned about them laying eggs in your house you can relax; they only want to get outside to find a mate. Even if an egg laden female found her way into your house she would only lay eggs on rotting food, not fresh.

      As far as the BSF in your house being “not pleasant” I must disagree. BSF are beautiful, harmless and beneficial creatures, not something repulsive. Each person is entitled to their opinion but this is, after all, the black soldier fly blog… :)

      I think that BSF larvae are migrating away from your compost bin and finding a way into your house where they’re pupating and emerging as adults. I recommend finding and plugging the gaps that the larvae are using to enter your basement.

  • June 24, 2010 at 6:51 pm

    how do black soilder maggots get in my house and bathroom. They are all in my house

    • June 24, 2010 at 7:13 pm

      Hi stephanie,

      First, the larvae must be developing somewhere on an adequate food source which is usually rotting food. If you have a compost pile or worm bin near the house that might be the source. Because they need a good quantity of food over a period of weeks before they can fully grow it’s not at all likely they’re maturing inside your house. Once matured the larvae crawl away from the food source in search of a safe dry place to pupate. They head out in a random direction (I assume) and some of them will end up crawling towards your house. Of course at that point they would need to find a crack to enter the house.

      One other possibility exists since you’re finding them in the bathroom. BSF will breed in human waste and they might be finding a way to enter your septic system. In theory if the larvae are developing in your septic tank or waste pipes they could be crawling through the pipes and entering the bathroom via the toilet, sink or bathtub drains. They would have no problem passing through flooded sections of pipe. You see, it’s possible they could enter the septic/drain system through a small opening because when they first hatch they’re very tiny. Once they grow to their full size they might not have any other exit than through the pipes and into your bathroom. The BSF females are good at locating waste and if they’re finding even a small opening in the septic system they can lay their eggs on the outside of it and the newly hatched larvae will crawl inside and develop. If you’re finding them in the tub or sink I would think this is the situation.

      All you need to do to stop the intrusion is to find and seal whatever openings are allowing the larvae to enter the house directly or through the waste pipes.

  • June 27, 2010 at 4:31 pm


    Do you have a place on your blog that lists the supplies needed to build the composter? I’ve seen pictures and illustrations, but I haven’t located the list of needed materials yet. I thought it would be best to start with all the needed supplies before I try to build one.

    thanks so much!


    • June 27, 2010 at 4:46 pm

      Hi Kristi,

      I’m building a v2.1 unit as I type. I’m taking more detailed photos than before and I’ll post a parts list very soon.

  • July 24, 2010 at 8:36 am

    I have adult black soldier flies in my finished basement. Is this a problem? Do they eat wood timbers or wood foundations? What is their food source and how would I identify it? Even if they are not a problem, I would like to get rid of them – how can I do this?


    • July 26, 2010 at 8:26 am

      Hi Margaret,

      First, no, BSF adults cannot harm your house or you. BSF adults (winged stage) do not eat as their only purpose in the few days they live as adults is reproduction. It’s very unlikely that the BSF are entering your house as adults; it’s much more likely they’re crawling in as larvae and then pupating. You need to find out how the larvae are entering your basement. The following link is a reply I gave someone else with BSF in a basement. The details might be different for you but the answer may be helpful anyway:

  • July 26, 2010 at 12:04 pm

    I keep my bin so close and, since I am not feeding fish with them ATT they just wander off from their food source, sometimes into my house, to pupate. Notably when it’s rainy At that time, even tho the larve still have mouths, they are no longer eating any more.

  • August 26, 2010 at 10:48 pm

    Okay, tell me how BSF’s end up in my toilet. I have an enclosed septic system… only recently these ‘flies’ have become a problem. and only recently have we started serious composting. The compost bin is 150 ft from the house. there are no apparent leaks in the system. We are not bothered by an abundance of flies in the air. Help me to understand so I can eliminate an embarrassment when company comes. thank you.

    • August 27, 2010 at 7:35 pm

      Hi Frank,

      Maybe it’s best if we start at the point where BSF females lay their eggs. Your septic system has drains and vents and the BSF must be coming from one of those sources. The vents might be a good candidate because they supply an easy entry point. If you want to investigate that possibility I recommend placing strips of corrugated cardboard or plastic around the vent outlet. The voids in the corrugated material are attractive egg laying sites for BSF, and it is easy to see when eggs have been deposited. In the past I’ve answered this question only based on the idea that the larvae must be from eggs laid near a hole in the tank or drain pipes, but I think the vents represent a higher probability.


  • October 28, 2010 at 9:30 am

    These BSF got into our commercial composting toilet and we had the hardest time figuring out what the heck they were. This article was very helpful. So — they DO get into houses. But it wasn’t a big deal. They are probably actually quite helpful in processing the material. Just disconcerting when something comes buzzing up against you when you are doing your business… We do cold composting inside with our toilet (we are off the grid so can’t have a “heater” in the toilet. and have hot composting outside in a compost pile where we mix other stuff in. Their larvae are present there in abundance but I didn’t know what they were before. I’m glad to know.

    • October 28, 2010 at 9:40 am

      Hi Susan,

      What I and others promote is the idea that BSF adults don’t normally enter houses, but most houses don’t contain manure. I assume that the composting manure in your toilet does not have a strong odor, but rest assured, BSF females are experts at locating manure and rotting food, even if the scent isn’t noticeable to humans. Your attitude about the BSF is refreshing and I hope you can find a way to deal with them that makes everyone comfortable. Thanks for sharing.

  • October 28, 2010 at 5:28 pm

    Yep — We have to have a pipe vent that goes out onto the roof. It is not electric, but is driven by the updraft of the air coming off the material in the toilet. The only thing electric are two small DC fans which do keep the smell away from us and also help dry the material somewhat so that it composts in a mostly aerobic environment. I’m sure that the flies came through the roof vent, where the smell is sure to attract them. We could probably put a screen or something in the vent, but I’m not sure we want to do anything to prevent them. They are much more pleasant than many other insects that could get in there and they are very helpful. We have a hinged screen in the bathroom window, so it’s easy to let them out and they are, indeed, beautiful as you say.

    • October 29, 2010 at 10:12 am


      It’s nice that you and your family is able to appreciate the BSF. I’m curious about the effect of the larvae on the compost. If you live in Ohio as your email address indicates, I would expect that the adult BSF are finished for this year, but the larvae may survive through the winter in your compost. It would be great if you can provide occasional updates on your observations.


  • November 2, 2010 at 2:06 pm

    I am back. The last two years we had abundant soldier fly larvae. This year almost nothing and thus our compost isn’t nearly as good. What is the best way to bring them back again? Atlanta, GA

  • November 22, 2010 at 12:37 pm

    hi, im from venezuela, last month a friend went to USA and brought me 25 bsf larvae, im pretty sure that we dont have bsf in venezuela or at least not in my city, so im trying to breed them in order to build a bio composer and feed my reptiles. im afraid that im running out of time by waiting for the bsf to mate, i keep the flies in a glass terrarium of 80x50x70 cm with some plants and the compost inside a carton box with some holes so the flies cans get inside it, the temperature is on 86 and the humility is on 90% , but they dont even try to made. what can i do? is there any advise for activating their mating sense?. i have only 12 flies left. i need help

    P.S: excuse my bad english

  • December 29, 2010 at 1:12 am

    Hi! I’m a vermicomposting addict, but I must say this is very intriguing to me.

    I’m from Manila and I can’t seem to find suppliers for BSF.

    Any ideas?


    Great anecdote. Makes me want to find BSFs in my compost bins too!

  • July 11, 2012 at 7:11 pm

    I have found two black soldier larva in our commode lately. How can this happen and what should I do about it. Can they climb from septic tank through pipes to commode. I know this is what it is because I looked it up, and it was identical to all pictures. I have read that they are beneficial to septic tank but I don’t like them in commode.

    • July 11, 2012 at 9:49 pm

      Hi Janice,

      I imagine BSF larvae could navigate sewer pipes but the question is how are they entering the system in the first place. BSF larvae are tiny when they first hatch so a pinhole is enough to let them in.. Since BSF females lay eggs near waste including excrement maybe they’re laying on a vent pipe on the roof after being attracted to the scent. BSF were traditionally found in outhouses throughout the south and were considered beneficial. I can understand why you wouldn’t want them in your commode, but if you’ve only had two make the journey I expect it would be a rare event. I would just flush them and keep an eye on the situation. I can’t think of a remedy assuming that your septic system is functioning properly. Please let us know if you keep having the same problem.

  • July 11, 2012 at 11:52 pm

    The sewage pipe actually has enough air to allow larve or rodents to move about. That they are coming up in your toilet DOES mean you have some pipe breach that is open to air, might be improper venting, which won’t be too expensive but may vent noxious gases into the house, or there is some damage somewhere.

  • July 12, 2012 at 9:05 am

    Thank you, We had septic repairs last summer and the top was off the tank for a day or so could they enter then and just now be showing up? I do have someone coming to check pipes under house. I guess I could have them check vent on roof also. Will they harm the septic system and what happens when they cant get out to complete their change to black soldier fly? Do they die eventually in my tank. I was surprised you answered so soon. I appreciate it and thanks to your blog now I’m not scared of them.

    • July 12, 2012 at 10:57 am

      Thanks for the feedback Pego, the more the merrier!

      Janice, the top being off the septic tank may be the answer. I’ve personally had larvae take 6 months to develop due to cool temperatures so 9 or 10 could be possible. Being underground would keep the temperature cool even in warmer months. Concerning the roof vent; even if the BSF were attracted to the vent I don’t know what you could do the prevent that. I’m less enthusiastic about the vent theory since virtually every house has them and this is a rare occurrence.I wouldn’t bother with that unless maybe you have an ongoing issue. The larvae will not harm your septic system in any way and if they can’t escape they’ll simply die and decompose with the other waste.

  • July 12, 2012 at 7:41 pm

    Thank you Jerry, I feel much better now. It rained here today so I still haven’t had the pipes checked. Your blog is so interesting now I’m reading all about the BSF. I kinda feel bad that they can’t complete their life cycle. Thanks again

  • August 2, 2012 at 9:06 pm


  • August 18, 2012 at 11:34 pm

    I keep looking for new info on any zoonotic parasite studies and it looks like some should be forthcoming. Did you see BSFs showing up at this? http://news. bill-gates- toilet-challenge -spills-forth- 071550616. html?_esi= 1

    They did a BSF composting toilet prototype!

  • August 31, 2012 at 1:51 pm

    Where do BSF’S come from. They just showed up from nowhere. What’s there purpose?

Comments are closed.