BioPod spring cleaning

This is a log of everything I will add to and remove from my BioPod this year including BSF grubs harvested. I will give an exact weight and general description of the waste added. The data will include the weekly and monthly ratio that waste is converted into grubs.This begins with a spring cleaning of my BioPod after which I added a small amount of compost and a few hundred BSF grubs from last year’s colony. These grubs were laid in the fall of last year and kept through the winter by insulating the BioPod. Of course the moisture content can vary a lot (dry tea bag/wet tea bag) and this makes a significant difference in the weight, so please use this log as a very general reference.

It will take a few weeks before the first new grubs begin to mature and self harvest. Until then there won’t be much to remove. Once the first generation begins to mature we’ll start to see what kind of ratio of food scraps to grubs I get. Converting food waste into grubs is called bio-conversion and there have been reports of ratios everywhere from 8% to 24% waste/grubs.

I often collect eggs from my BioPod before they can hatch and I use these in starter kits for our BioPod customers. I also harvest juvenile grubs and many times this includes a significant percentage that are very small. I’m not sure how this might effect the conversion ratio but I thought it was worth mentioning.

I will be weighing using the metric system and roughly converting to ounces.

May 3, 2009 waste in = .4kg
  • Sat + 14 oz (.4kg) bread
May 4-10 waste in = 1.4kg
  • Tue + 10 oz (.3kg) coffee grounds
  • Wed + 15 oz (.42kg) banana peels, raw potato, used tea bags
  • Wed + 8 oz (.23kg) wet spoiled fish food
  • Sun + 16 oz (.46kg) fruit, bread, cheese, rice
  • average daily input = 5oz (.14kg)
May 11-17 waste in = 2.9kg grubs out = .04kg conversion rate 1%
  • Thur + 9oz (.25kg) coffee grounds, 18oz (.5kg) bread, banana peel, canned tomato
  • Sat + 10oz (.3kg) corn grits, tea bags (5 large), fruit peels, 2oz (57gm) dry fish pellets
  • Sat – removed 1.4oz (40gm) mature grubs which was .5 cups (115ml). (403 grubs)(yes, I counted them) :)
  • Sun + 7oz (.2kg) bread, rice, fruit, 1 lb 11oz (.78kg) whole fish
  • average daily input = 11oz (.3kg)
May 18-24 waste in = 3.12kg grubs out = .037kg conversion rate 1%
  • Mon + 11oz (.31kg) whole fish, 9oz (.26kg) muffin, fruit, veg
  • Tue + 13oz (.38kg) whole fish
  • Wed + 9oz (.25kg) coffee grounds, muffin, 9oz (.25kg) whole fish
  • Thu + 5oz (.15kg) whole fish
  • Thu – removed 1.3oz (.037kg) mature grubs
  • Fri + 10oz (.28kg) whole fish, 25oz (.7kg) chicken skin, fruit, dog food, seeds
  • Sat + 14oz (.4kg) cornmeal, 5oz (.14kg) fruit peels
  • average daily input = 16oz (.45kg)
May 25-31 waste in = 13.88kg grubs out = .44kg conversion rate 3%
  • Tue + 13oz (.36kg) whole fish & scraps, 15oz (.45kg) apple, cornmeal, coffee
  • Wed + 86oz (2.44kg) cucumber, apple, banana
  • Thu + 2oz (.05kg) whole fish
  • Thu – removed 1oz (.035kg) juvenile grubs
  • Fri + 13 lbs 3oz (6 kg) melon rind and a few figs
  • Fri – removed 8 oz (.22kg) mature grubs
  • Sat + 7.14 lbs (3.24kg) melon rind, 7oz (1.9kg) cornmeal, whole fish
  • Sun + 6oz (.16kg) whole fish
  • Sun – removed 7oz (.19kg) mixed grubs
  • average daily input = 4.375 lbs (2kg)
June 1-7 waste in = 5.82kg grubs out =1.02kg conversion rate 17%
  • Mon + 8oz (.23kg) whole fish
  • Tue + 6oz (.16kg) fish, 15oz (.43kg) coffee, fruit, bread, tea bags
  • Wed + 35oz (.98kg) chicken hearts, beets, chili + 6oz (.17kg) fish
  • Thu + 8oz (.24kg) bread, 6oz (.17kg) fish
  • Fri + 31oz (.88kg) salsa, fruit, bread, coffee, 21oz (.6kg) whole fish
  • Sat + 3oz (.097kg) whole fish, 33oz (.93kg) damp grass seed
  • Sun + 31oz (.89kg) rice, teabags, fruit, 2oz (.044kg) fish
  • Sun – removed 26oz (.749kg) juvenile + 9oz (.268kg) mature grubs
  • average daily input = 1.8 lbs (.83kg)

BSF harvest - mature 6-7-2009 BSF harvest - juvenile 6-7-2009

(click images to enlarge)

The photos above are of the grubs harvested on June 7th. The dark grubs are the final larval stage (prepupae) and these were removed from the collection bucket of the BioPod. The light colored grubs are juveniles and I removed them directly from the food pile using the technique I describe HERE. The brown paste on the juveniles is some of the remaining fish food that I used to attract them when I collected them. Also you can see some juvenile grubs mixed in with the mature ones from the collection bucket. They probably migrated out of the BioPod because it was getting too hot inside. If this happens to you and you would like an easy way to return the juveniles to the colony simply dump all of them back into the unit. Assuming it’s cooler inside the juveniles will probably stay while the mature grubs return to the ramps and back into the collection bucket.

June 8-14 waste in = 10.173kg grubs out =.889kg conversion rate 9%
  • Mon + 25oz (.697kg) whole fish, fish carcass, 56oz (1.574kg) melon
  • Tue + 20oz (.569kg) coffee grnds, bread, cornmeal, 6oz (.158kg) fish
  • Tue – removed 1.4oz (.04kg) juvenile grubs
  • Wed + 86 oz (2.446gk) raw corn kernels
  • Wed – removed 6oz (.176kg) mature grubs – 17oz (488kg) juvenile grubs
  • Thu + 9oz (.255kg) canned pet food, banana peels
  • Fri + 31oz (.884kg) whole fish and scraps
  • Sat + 6oz (.165kg) whole fish, 6oz (.170kg) tea bags, cat food
  • Sun + 77oz (2.189kg) whole watermelon, 38oz (1.066kg) peaches
  • Sun – removed 7oz (.185kg) mature grubs
  • average daily input = 3.2 lb (1.45 kg)
June 15-21 waste in = 3.85 kg grubs out = 1.19kg conversion rate 31%
  • Mon + 5.5 lb (2.5kg) whole watermelon
  • Mon – removed 7oz (.185kg) mature grubs
  • Tues – removed 6oz (.179kg) mature grubs
  • Wed + 35oz (.986kg) whole fish, 13oz (.365kg) coffee, berries
  • Wed – removed 24oz (.669kg) mature grubs
  • Fri – removed 6oz (.16kg) mature grubs
  • average daily input = 1.2 lb (.55kg)
June 22-28 waste in = 4.753kg grubs out = 1.007kg conversion rate 21%
  • Mon – removed 14oz (.399kg) mature grubs
  • Tue + 3.3 lbs (1.514kg) bread, bananas, tea bags
  • Wed – removed 13oz (.361kg) mature grubs
  • Thu + 1.4 lb (.618kg) onion, tea, coffee
  • Thu – removed 2.6oz (.073kg) mature grubs
  • Fri + 14oz (.408kg) dry cornmeal, 6oz (.183kg) whole fish
  • Fri – removed 2oz (.050kg) mature grubs
  • Sat + 17oz (.472kg) coffee, tea, fruit, 4oz (.123kg) whole fish
  • Sat – removed 4oz (.124kg) mature grubs
  • Sun + 3.2 lb (1.435kg) watermelon rind
  • average daily input = 1.2 lb (.55kg)

Month of June: waste in = 29.527kg grubs out = .910kg conversion 14%

June 29-July 5 waste in = 10.42kg grubs out = .945kg conversion 11%
  • Mon + 3.2 lb (1.428kg) cornmeal, cabbage, tea bags, 15oz (.416kg) whole fish
  • Tue + 6.8 lb (3.087kg) watermelon
  • Tues – removed 3oz (.086kg) mature grubs
  • Wed + 6oz (.166kg) whole fish
  • Wed – removed 2oz (.051kg) mature grubs
  • Thu + 2.5 lb (1.153kg) whole fish and scraps
  • Fri + 2.7 lb (1.224kg) whole fish
  • Sat + 7oz (.221kg) fish, 19oz (.545kg) coffee, tea, fruit, veg
  • Sun + 3.9 lbs (1.788kg) watermelon, 10oz (.282kg) coffee, wet cornmeal, 4oz (.112kg) fish
  • Sun – removed 1.2oz (.035kg) mature grubs, 1.7 lbs (.773kg) juvenile grubs
  • average daily input = 3.3 lbs (1.489kg)

It’s been about 9 weeks since I cleaned out my BioPod and restarted the colony using a few hundred BSF grubs from last season. At the beginning of this log I posted a photo of my BioPod as it looked that first day and I thought it would be good to show you what my colony looks like now. Below is a series of photos taken over a span of 5 or 6 hours on July 2nd when I added 2.5 pounds of whole fish and fish trimmings. By the next morning there was nothing left of the fish except for the bones.

BioPod colony 7-2-2009 11am 120px BioPod colony 7-2-2009 11am-plus fish BioPod colony 7-2-2009 1pm BioPod colony 7-2-2009 3pm

(click images to enlarge)

To be fair I need to point out that this is my third season culturing BSF on my property. I’ve built up a very healthy population by protecting thousands of BSF grubs through their larval stage, a period when the vast majority of wild grubs would be eaten. I also live in the southeastern U.S. which is the native range of the black soldier fly. Someone just starting out with BSF might not be able to establish a colony as robust as mine in just a few weeks, especially in an area where BSF are relatively scarce.

A few days after the fish series of photos above I took another series with watermelon. You can see some bones which are all that remain from the over 5 lbs of fish from the previous two days.

BioPod colony 7-5-2009 11.35am with watermelon BioPod colony 7-5-2009 11.45am BioPod colony 7-5-2009 12.10pm BioPod colony 7-5-2009 12.15pm close up

(click images to enlarge)

July 6-12 waste in = 9.526kg grubs out = 4.230kg conversion 44%
  • Mon + 4.3 lbs (1.944kg) whole fish
  • Tue + 14oz (.399kg) whole fish
  • Wed + 1.2 lbs (.551kg) ice cream, tea, fruit, 3 lbs (1.359kg) melon
  • Wed – removed 3.4oz (.097kg) mature grubs
  • Thu + 16oz (.450kg) bread, soup
  • Thu – removed 1oz (.027kg) juvenile grubs
  • Fri + 3.3 lbs (1.489kg) wet cornmeal, 5oz (.140kg) coffee, 9.2oz (.262kg) fish
  • Sat + 4 lbs (1.819kg) melon
  • Sat – removed 16oz (.449) mixed grubs, 8 lbs (3.657kg) juvenile grubs
  • Sun + 2.5 lbs (1.113kg) whole fish
  • average daily input = 3 lbs (1.361kg)

Notice that on Saturday of this week I removed eight pounds of juvenile grubs from the BioPod. That’s a lot of BSF grubs. Removing them lowered the level in the unit by more than two inches. As mentioned previously I used a method for removing the juvenile grubs that you can find HERE. Taking out such a large amount at one time resulted in the very high conversion ratio for this week, but with a much smaller colony going into next week we’ll see a correction in the ratio. This batch of grubs were all light-colored juveniles and ranged in size from almost full grown to only a few millimeters long. If these grubs had all been allowed to reach full size then the volume and weight would have been several times more.

The reason I harvested such a large quantity of juvenile grubs is because I’ll be traveling for over a week. Had I left these grubs to mature there would have been a constant stream of mature grubs dropping into the collection bucket while I was out of town. I could have asked my girlfriend to collect them, but I didn’t want to ask her to weigh each batch as I’ve been doing for this log.

Due to this situation I’ve realized that removing juvenile grubs can be a useful management tool for BSF culturing. With such a robust colony my BioPod was running at full capacity and required more careful and regular attention. By scaling back the size of my BSF colony I was able to lower the intensity level to the point where it could left alone for a few days at a time.

The grubs in the photos below are part of the eight pound harvest. I repeated this process a total of three times.

Juvenile BSF grub collector Juvenile BSF grub collector-baited 4.47pm Juvenile BSF grub collector 4.55pm Juvenile BSF grub collector 5.21pm Juvenile BSF grub collector 5.43pm

(click images to enlarge)

July 13-19 waste in = 3.4kg grubs out = 0kg conversion 0%
  • Mon + 13.3oz (.378kg) fish scraps, 2.5 lbs (1.149kg) squash, cherries
  • Tue + 4oz (.119kg) coffee grounds
  • Thu + 2.2 ibs (.996kg) cornmeal paste
  • Sun + 1.6 lbs (.748kg) cornmeal paste
  • average daily input = 17oz (.484kg)
July 20-26 waste in = 5.56kg grubs out = 1.429kg conversion 26%
  • Tue + 2 lbs (.947kg) cornmeal paste
  • Thu + 2.8oz (.079kg) whole fish
  • Fri + 4 lbs (1.822kg) watermelon rind, 15oz (.414kg) fish
  • Sat + 12.6oz (.356kg) whole fish
  • Sun + 4.3 lbs (1.942kg) cornmeal paste
  • Sun – removed 3.15 lbs (1.429kg) mixed grubs
  • average daily input = 1.75 lbs (.794kg)

Month of July: waste in = 29.527kg grubs out = 7.43kg conversion 25%

July 27- Aug 2 waste in = 6.659kg grubs out = .905kg conversion 14%
  • Mon + 5.1 lbs (2.321kg) melon, 1.4 lbs (.612kg) coffee, bread, snake (killed by dog)
  • Tue – removed 2 lbs (.905kg) juvenile grubs
  • Wed + 14oz (.399kg) pasta Alfredo, whole fish
  • Thu + 2.25 lbs (1.927kg) melon rind, 5oz (.137kg) whole fish
  • Fri + 11oz (.316kg) vegetables and grains
  • Sat + 10.4oz (.295kg) fish, 11.6oz (.329kg) Ortega mild green chili sauce
  • Sun + 11.3oz (.321kg) whole fish
  • average daily input = 2.1 lbs (.951kg)
Aug 3-9 waste in = 7.506kg grubs out = 1.543kg conversion 21%
  • Mon + 1.4 lbs (.616kg) whole fish
  • Tue + 4.6 lbs (2.073kg) melon, rice, coffee, onion, 2.4oz (.069kg) fish
  • Wed + 7oz (.206kg) pears, coffee
  • Thu + 10oz (.290kg) fish
  • Thu – removed 2.8 lbs (1.262kg) juvenile grubs
  • Fri + 1.5 lbs (.690kg) pears
  • Sat + 7.2 lbs (3.254kg) whole watermelon, 10.9oz (.308kg) fish
  • Sun – removed 10oz (.281kg) mixed grubs
  • average daily input = 2.4 lbs (1.07kg)
Aug 10-16 waste in = 2.86kg grubs out = 0kg conversion 0%
  • Thu + 3.74 lbs (1.695kg) watermelon rind
  • Sat + 1.5 lbs (.697kg) fish
  • Sun + 10oz (.279kg) coffee, banana, 7oz (.193kg) fish
  • average daily input = 14.4 oz (.409kg)

close up of adult BSF

I thought it might be a good time for a photo. :) Black soldier flies rarely land on people but this one had just emerged from pupation so I was able to admire it for a few minutes before it flew off in search of a mate.

Aug 17-23 waste in = 10.02kg grubs out = .333kg conversion 3.3%
  • Mon + 5 lbs (2.306kg) melon rind
  • Thu + 3.4 lbs (1.527kg) melon, 7oz (.212kg) coffee grounds
  • Thu – removed 1.5oz (.043kg) mature grubs
  • Fri + 2.8 lbs (1.286kg) melon, 12oz (.345kg) fish, 9oz (.252kg) bread
  • Sat + 9 lbs (4.094kg) Kieffer pears*
  • Sun – removed 10.2oz (.29kg) mature grubs
  • average daily input = 3.16 lbs (1.432kg)

*Kieffer pears are an old hardy variety that doesn’t get soft like most. It’s used for cooking and canning and I’m curious how long it will take the colony to consume them. These pears added a lot of weight to this week’s total which should be balanced out by significantly higher ratios in the near future.

Update: apparently the Keiffer pears aren’t as hard as they seem, at least not to the grubs. :) They were mostly eaten within a few days.

Aug 24-30 waste in = 4.99kg grubs out = .474kg conversion 9%
  • Wed – removed 2.6oz (.075kg) mixed grubs
  • Thu + 5.3 lbs (2.394kg) cooked rice, 2.3 lbs (1.026kg) fish
  • Fri + 8oz (.226kg) coffee, 3 lbs (1.344kg) cornmeal paste
  • Fri – removed 6.6oz (.188kg) mature grubs
  • Sat – removed 7.4oz (.211kg) mixed grubs
  • average daily input = 1.6 lbs (.713kg)
Aug 31-Sept 6 waste in = kg grubs out = kg conversion %
  • Tue + 9.2 lbs (4.154kg) Keiffer pears, 10oz (.285kg) fish
  • Thu – removed 1.5oz (.043kg) mature grubs
  • Fri + 2.5 lbs (1.124kg) Keiffer pears
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. 😉

38 thoughts on “BioPod Log-waste in-grubs out

  • August 13, 2009 at 5:01 pm

    Awesome research! Don’t know if the scientists would consider this a totally accurate analysis, but it speaks volumes (literally) about the success of using BSFL to compost. I just wish I could attain the success rates that you’ve achieved!

  • August 13, 2009 at 5:06 pm

    Thanks Daniel!

    If you keep at it you’ll eventually get a good colony going.

  • August 14, 2009 at 1:00 pm

    Your totals to date look to be:

    waste in 89.367kg grubs out 13.675 conversion of 15.3%

    It will be interesting to see the final numbers in the fall.

  • August 14, 2009 at 1:51 pm

    Thanks Mike. It’s funny I guess but I hadn’t gotten around to looking at the running total yet.

    15% seems like a decent ratio. I wonder what effect all of the fish has had. I did a quick estimate recently and I think fish represents around 25% of the total waste added.

    Also, I live in fear that I’ve made a mistake in the calculations somewhere so if anyone cares to check my work I won’t take offense. :)

  • August 14, 2009 at 2:10 pm

    The present ratio of grubs to waste in the BioPod is the unknown at this point. Your post about removing eight pounds of juvenile grubs which lowered the level in the unit by more than two inches hints that a lot of the weight of the BioPod contents is grubs.

    I’m guessing that most of the weight/volume is grubs which would improve the final conversion value.

  • August 14, 2009 at 3:25 pm


    I recently removed the contents of my BioPod temporarily to install a pre-filter on the bottom of it. I observed a fair number of grubs, but I estimate they would only add up to about 5% of the total weight. However, I believe I could stop adding any new food and still probably see a large number of BSF develop on the nutrients still contained in the current compost.

  • August 14, 2009 at 4:04 pm

    I wonder if harvesting immature grubs has an effect? Logically they would have eaten more during the period while they matured.

    So many unknowns/questions :)

  • August 14, 2009 at 4:48 pm

    I wondered about that too. A large percentage of the eight pounds of grubs I removed were small. Some of them would have increased in size by 10 times or more. Of course to grow them I would have needed to add even more food…

    Many questions…

  • September 20, 2009 at 3:08 pm

    Jerry your totals to date are:

    waste in 112.515 kg grubs out 14.525 conversion of 12.9%

    Is that it for this season?

    If you do this again it would be interesting to record volume too.

    • September 21, 2009 at 10:53 am

      Hey Mike,

      No, I haven’t stopped processing waste or logging the data, I’m just behind in updating the log. As you know I removed the compost a few weeks ago and I’m in the process of separtating the larvae from it. I’m returing the separated BSF back to the BioPod to build up the colony in preparation for winter composting. A large percentage of the BSF in the BioPod are small so I think I’ll have a healthy size colony still when mating ends for the year.

  • September 21, 2009 at 11:09 am

    Good to hear that you’re not done for the season. How are you separating the larvae from their leavings (pudding)? There are some techniques for doing the same with earthworms that might be of interest (both species are photo-phobic)

    • September 21, 2009 at 12:34 pm

      Here’s a rough diagram of the set up I’m trying.

      compost separator

      In about two weeks I’ve removed 90% of the BSF. The remaining larvae are mostly mature or preparing to enter that stage. I’m hoping that when I add worms to the compost, either in this container or a non-perforated bin, that the action of the worms will help motive the mature BSF to migrate out.

  • September 21, 2009 at 1:32 pm

    Hi Jerry,
    When you talk about totes, you mean something like a large bucket, right? When I, being British, think of the word ‘tote’, I think of toting, i.e. carrying something; or a woman’s handbag… Now surely you’re not putting BSF larvae into something by Louis Vuitton, Gucci or Prada!

    • September 21, 2009 at 1:47 pm

      Um, yes Alan, I mean a storage container and not high fashion apparel. 😉

      I do see a day in the future when BSF larvae replace Chihuahuas as the trendy “accessory pet”.

  • September 30, 2009 at 12:28 am

    I was thinking about ways to clean out the contents of my biopod, and it it occurred to me that maybe heating it up to the point where the grubs would crawl off would work. Then I thought maybe I should put the contents into a metal bucket tilted at an angle and shine a nice hot work light at the bottom of the bucket. Since a ramp would be available to escape I think they might harvest themselves rather than be cooked in a bucket of muck.

    I have also been working for awhile on ways to thermostatically heat the biopod so it could remain useful in the winter and allow earlier boot up in spring. This feature might also be useful for chasing the grubs out for cleaning if it works as I suspect. Obviously since the biopod is plastic I would need to be careful not to overheat it. Any idea what temp causes crawl off?

    It’s cooling off here in Dallas and the pod is slowing down considerably, although I did see some adults today (it was about 80 degrees out). Probably should move the pod to where it will get some sun on it.


  • November 13, 2009 at 9:38 am

    I am teaching a middle school science class where the students are tending a biopod. We have about 1600 grubs in the pod right now and we are looking to start a second one using lunchroom scraps. I live in NW Alabama where the temperatures can drop into the teens at night. Do you have any pictures or advice on ways to easily insulate the pod? They are not the easiest shape to add foam board or anything like that to. Ideas would be great. We are going to try to document our adventures on line similar to yours. Thanks for the help.

    • November 13, 2009 at 11:47 am

      Hi Jayson,

      You don’t need to insulate the outside of the unit. The simplest method for insulating the colony is to cut a disc of Styrofoam and place it directly on the pile. Place new waste under the disc and the larvae will concentrate there.

      At this time of year it’s not likely that you’ll get reproduction, and 1600 larvae is a tiny colony. A full size colony in a BioPod could possibly be 100 times that number or even more. Keeping a colony outdoors in the winter is dependent on them generating heat from metabolizing food waste, and this will be tricky with so few BSF. The larger the colony the easier it should be to keep them active and eating through the winter months. I sell BSF larvae and if you’re interested in enlarging your colony I’ll give the school a special price.

      I don’t now of a comprehensive source of information about culturing BSF in cold weather, but I’ve started a topic at the BioPod forum which might be a good starting point:

      Good luck and feel free to ask any questions.

  • November 13, 2009 at 3:22 pm

    Insulating the biopod is a bit tricky but it did the trick for me. When the evening temps here in Dallas dropped into the 40’s the pod food consumption dropped dramatically. Now it is operating at full capacity, and the temps stay around 90 F because of the grubs.

    I inserted a styrofoam layer under the unit and then wrapped it in several layers of bubble/foil insulation, and taped it up with metal foil tape. The foam layer underneath required a different connection tube, which I made from a sink drain. I removed the stock filter and went to a large flat filter pad that is working well. A few grubs get past but they did before also.

    I also added an insulated disk on top of the colony as Jerry recommends. I built a small thermostatic heater for the BioPod, but the insulation alone has been enough to keep the colony warm and happy and by the time that they need electric heat they will probably be all done and self-harvested anyway. We’ll see what happens when it gets colder.


    • November 13, 2009 at 3:37 pm

      Dave, I’ll bet that with outer insulation as well as an internal disc you won’t need a heater if you feed consistently. The additional heater could come in handy though, if the feeding schedule gets interrupted.

      I don’t think you’ll see all of your larvae maturing and harvesting. Without any special effort last year I had a medium density colony of juvenile larvae that remained in that stage for about 5 months through the winter. I’m now seeing nighttime temps in the 40’s (F), but I haven’t installed any insulation because I want to stall the development of the juvenile larvae in order to keep them in that stage this winter. I honestly don’t know if keeping them insulated now would encourage faster maturation, but I’m acting on the assumption that it would.

      I’ve been saying that the breeding season ends in October here in south Georgia and I need to amend those statements. Today is November 13 with the high temperature at about 73ºF (23C) and I’m seeing egg laying activity. I’ve seen adult BSF emerging from pupation in temperatures in the 60’s. This helps me understand how there can be wild BSF populations commonly found in Seattle and even Vancouver, BC. I also recently was told of wild BSF occurring in central Illinois which surprised me even more.

  • November 22, 2009 at 8:26 pm

    I’m having the opposite problem of having to insulate. Though I’ve cut feeding WAY back, I have an 8 inch thick (at least) solid mass of squirming grubs on the surface of my biopod! I can feel the heat rising off the BioPod whenever I lift the lid. I keep the lid shimmed up so as to provide additional air flow across the surface, but still have heat issues. Every morning I have as much as half a bucket from the collection bucket full of grubs. Though some are pre-pupal grubs, most are not. I think they crawl off just to escape the heat! The so-called “pudding level” has dropped to almost nothing! The BioPod is just crammed full of grubs to within inches of the top of the ramp!

    The three buckets of overflow grubs from the biopod have not been fed more than once in the past 3 weeks. When I lift the bucket lids on those containers, there are no grubs evident, but down an inch below the pudding surface, they are thick! I am still seeing egg laying inside the lids of the DIY buckets too (though none inside the BioPod).

    Our daytime temps here are still in the low 80’s and nights are high 50’s to low 60’s. If my population keeps growing at the current rate, I’m going to need more buckets! Remember that 1950’s sci-fi movie, “The Blob”? Where the blob kept doubling in size every so often? That’s kind of what my BSF grubs remind me of!

    I’ll post a movie soon of my colony. And in another thread, I’ll post the results of my ill-fated BSF grub oil extraction experiment!

    • November 24, 2009 at 9:14 am

      Brian, it’s not uncommon for juvenile larvae to crawl up the ramps to escape excess heat. Another way to deal with the heat is to leave the lid off during the daytime if your unit is protected from rain, or if you’re around to monitor it.

      BSF reproduction often happens in waves and it sounds like you have a tsunami on your hands. If you don’t want to deal with the excess grubs you can just release them, or feed them to something. Sooner or later reproduction will slow down due to cooler temps and your large mass of juveniles will mature. I believe you aren’t seeing eggs in the BioPod because the females “know” that the population is at the maximum. I assume this is due to chemical signals.

      I’m looking forward to your video!

  • November 27, 2009 at 3:19 pm

    “I’m looking forward to your video!”

    I finally got around to taking that video. The black round things evident on the surface are uneaten peels from deadfall grapefruits off my tree (finally found something the BSF grubs don’t eat!)

    It’s hard to judge depth in this video, but I was digging down a good eight inches with both the yogurt container and my bare hand. I want to emphasize that this population is just HALF of the original population! That was all I salvaged when I cleaned out the BioPod last month. The other half is in three, 5 gallon buckets.

    Here’s the video:

  • December 7, 2009 at 5:50 am

    Jerry, this is BSFfanatic! How have you been doing? Remember the large box idea of separating the composting worms from the bsfl? I finally got it built and going in Oct. of this year. Works very well for just messing around and getting rid of food scraps. Good thing we have a house of 8 and since I am the only one that really tries to eat left overs, the grubs get all of the spoiled food and most of the leftovers. The box is roughly 6 foot long, 15 inches deep, and about the same wide. I put a wall up in the center to divide the worms and larvae. I used a hole saw to put one big hole in the bottom of each end and tacked a screen over each of them to allow drainage and keep contents in. I also drilled many 1/8 inch holes in sides, ends, and bottom for extra drainage and breathing. I attatched 4 4×4’s for legs and so the box is up high enough that I don’t have to bend over and kids and animals can’t readily get into the top as was the case with my other totes, buckets, and box. In the larvae end, I have an oak board about 3 inches wide and the length got me about a 27 degree incline for an exit ramp that runs up to a small pvc pipe that they fall off into and then crawl through it a couple feet and drop straight down to whatever. I don’t have a bucket on it this fall/winter so they can go to the ground and my chickens get the ones that don’t hide good enough. On the other end of the box, are the compost worms and Canadian nightcrawlers. I have a large pvc tube that I drilled 5/8″ holes in the bottom part that is under the compost level and this is my worm tower which I am sure most of the readers out there are familiar with. This way, the cellulose type scraps/things that larvae don’t eat like celery I found out recently, go in there and the top is sealed off. This seems to be working for keeping bsf from laying eggs in that end. I have found adult larvae pupating in the worm end, but as of right now, they haven’t presented any problems with the worms. Remember the goal of the box idea was to find a way to raise both worms and larvae in the same area without the larvae taking over the worms habitat. I feed the worms some cornmeal every so often too and there are some old leaves in there for the canadians. I have the worm end of the box lower than the larvae end so as to keep the larvae drier and of course the extra moisture draining to the worm end is good for them. :)

  • December 12, 2009 at 7:01 pm

    Looks like my link to the video failed. Let me try again.

    My BioPod is solid grubs – nearly to the bottom. This video was taken last month, but now, mid-december, it is every bit at thick with BSF larvae. Our temps have been mostly in the 80’s here with occasional dips into the mid 70’s.

    Here’s the video:

    • December 13, 2009 at 12:05 am

      Brian, I’m still not seeing a link to the video. If you would like you can email the link to me and I’ll try from here.

  • March 27, 2010 at 7:05 am

    Temps. here are nearing 70. I’ve gathered that 75 is the magical temp. when black soilder flies start mating? How about the temp. when the newborn flies in the spring start to come out? Would it be about the same as 75?

    • March 27, 2010 at 7:41 am

      Hi Bill,

      You just reminded me that I need to input several weeks of data to complete this study. Someday soon I hope…

      Honestly I don’t know if there is a magical temperature for mating or the emergence of adults. BSF are found in such a wide variety of climates, for example the equator and British Columbia, and I’m not sure that one temp would “fit all”. I live in south Georgia and typically see emergence (and therefore mating) in mid April. Here the average high in April is 80º, average low is 53º, and average mean temp is 67º. In addition the weather in April is usually sunny with low precipitation which may be a factor.

      I would love to know when you see BSF.

  • March 29, 2010 at 10:33 pm

    Have seen a number of mature BSF within the past few weeks here in southwest Florida – despite the fact that our temps have been WAY below normal for this time of year.

    My mature BSF larvae that overwintered are self-harvesting rapidly now too. Had nearly 3/4 bucketful crawl out of my Biopod one day last week and land in the harvesting bucket!

    • March 29, 2010 at 10:48 pm

      Hi Brian, good to hear from you.

      What have the high temps been in your area when you saw the BSF adults? Was it sunny when you saw them?

  • March 30, 2010 at 5:57 am

    Jerry, it was sunny on the days I saw the mature flies, and temps were probably in the mid 70’s. Our average highs this time of year are normally in the low 80’s but we have seen only a few days that topped 80 during March.

    I have noticed that the big crawl-offs of mature larvae seem to occur when we have warm, rainy days.

    I did experience some crawl out of mature larvae throughout the winter, but the rate has definitely picked up during March. I bet I have 2 gallons of mature larvae in my bait freezer in the garage!

    Have not seen any egg-laying yet this year. My biopod is still chock full of larvae and I continue to feed sparingly, so maybe that’s the reason. No young larve either – all uniformly mature. I have noticed some fruit flies lately when I open the biopod. That was surprising, seeing as the biopod has an active BSF population going, but it leads me to wonder whether the pheromes that tend to keep other flies away are caused more by the young, growing larvae than by the old, nearly ready to pupate larvae.

    • March 30, 2010 at 8:50 am

      Brian your weather isn’t in the ideal range for BSF activity but we know it’s in the acceptable range. Thanks for reporting the sightings. Those adult BSF you’re seeing must be mating and laying eggs somewhere. If I were you I would keep an eye on the egg disc in your BioPod. BSF sometimes scatter eggs instead of laying in one spot. In that case you won’t know the eggs are there until 2-3 weeks later when the larvae become visible. Even at 3 weeks it’s hard to see the larvae in a waste pile.

      I have noticed some fruit flies lately when I open the biopod. That was surprising, seeing as the biopod has an active BSF population going, but it leads me to wonder whether the pheromes that tend to keep other flies away are caused more by the young, growing larvae than by the old, nearly ready to pupate larvae.

      I wonder if a lower level of activity in your BioPod is contributing to the presence of fruit flies. If you’ve had to reduce the volume of waste you’re processing it might result in less pheromones.

      Thanks for the updates.

  • May 5, 2010 at 9:57 pm

    Do you sell the large Biopod??

    • May 5, 2010 at 10:00 pm

      Hi Jim,

      I’m not selling any BioPods at this time. Even when I was a dealer it was very difficult to sell a large BioPod (ProtaPod) due to the very high shipping cost.

  • June 9, 2010 at 6:35 am

    I am rolling in larvae this year. I moved my larvae/worm box into my new chicken yard that is totally enclosed and the larvae go to the ground and help feed the 30 chickens in there. The problem this year is getting my family to understand that all scraps go into the scrap bucket for the larvae. And there is no need to keep the larvae and worms separated because the larvae make the food for the worms. You just need a large enough box or what have you so that the worms can keep lower for lower temps. and the larvae can stay up top constantly eating.

  • June 9, 2010 at 6:37 am

    Oh, Jerry, where can one buy a bio pod now?

    • June 9, 2010 at 11:10 am

      Hi Bill,

      I’m glad you’re rich in BSF this year. :)

      I’m not sure where to send you for a BioPod Plus, the original BioPods that I previously sold aren’t available in the U.S.

  • August 4, 2011 at 10:45 am

    Hello Jerry
    I was wondering how you protect mature larvae and see them become adults. My chameleons would love to eat flies.

  • December 25, 2011 at 7:37 am


    I have a complicated question and this may not be the right venue to raise it in; perhaps someone could direct me to an extension agent with more farm-specific information. I chose this blog because I could find you, and because you do seem to have some hard information, which I respect.

    I am a small farmer in Massachusetts. We rotate our animals on pasture all summer, but the winter confinement period is a good 5 months long. By next year, we expect to have a 5 month buildup of manure from 4 500 pound hogs and a 10-15 pigs, 300 laying hens, 4 cattle, and 20 goats and sheep. This manure will be mixed with a lot of carbonaceous bedding (less for the hens, since we have a collection area under their roost), and the plan in the spring is to scrape it out and put it in a couple of 8x12x4′ high compost bins, which could be insulated and covered with a film greenhouse cap. During the summer, there is a good deal less stuff to add — monthly chicken guts, maybe, and weekly additions of 8-10 buckets of coffee grounds from a nearby restaurant, occasional cleanouts of the hen’s range house. I would love to turn the winter’s manure into a high-protein feedstuff for the chickens and pigs, but the challenges I wonder about are these:

    1) sourcing enough larvae or eggs to make a dent in the pile early in the year. 1000 larvae for $36 would be pretty exorbitant by the time it made much difference.

    2) keeping a dormant colony of larvae through the winter. A compost pile of the size mentioned does not freeze solid in the winter, even though temps do not get above freezing outside for about three months straight. Microbial action usually keeps the center around 60-70; however, that little microclimate is surrounded by a block of ice. It might do better insulated and covered with greenhouse film; haven’t kept temperature records of that system yet. However, outside temps wouldn’t be ideal for the little guys from October through May (eight months!), so any reproduction which occurred during that time would have to be in the greenhouse/composting shed. I could probably keep a bush in there — what else do they need?

    3) irregular supply of feedstuff. I basically have a really big pile once a year. I could wait a few months to spread it. Could I put a relatively small number of larvae (say, 50,000) in a big pile of poo that has already been either frozen for a long time or microbially composting for a couple of months, and just let them reproduce until they’ve et it up, or would they be unable to eat older material? Tell me more about the problems with overfeeding.

    Thanks for your time.

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