Collecting the immature larvae

This method doesn’t involve the dark, prepupal larvae which are self-harvesting

The coffee colored BSF larvae (prepupae) are the final stage before pupation into adult BSF. To our advantage they are programmed by nature to crawl away from the food source in search of a suitable pupation site. In a properly designed BSF unit these larvae crawl up a ramp and drop into a collection bucket where they will live for weeks without any maintenance.

The method described below is for harvesting the earlier stages when the larvae are actively feeding and growing. It doesn’t work for the mature larvae because they don’t eat therefore aren’t attracted to the bait in the collection container. It works very well for the light colored immature larvae.

The Immature Larvae Collection Device or ILCD (old butter tub)

Take a cheap container and cut some small holes around the bottom edge.

immature larvae collector with fish pellets

(click on images to enlarge)

Add something delicious (any food scraps will do), and simply place it on the surface of the compost. I used fish food because I’m training my fish to eat it and this is a good way to introduce them to the flavor (I feed the larvae to the fish). Just about anything will work, but drier items might make handling the collected larvae easier.

The photo below was taken 2 minutes after placing the tub on top of the compost.

immature larvae collector after 2 min

This is after 11 minutes.

immature larvae collector after 11 min

The photo below was taken 40 minutes after adding the container.

immature larvae collector after 40 min

This quick harvest totaled about 2 cups (.5 litre) of small to medium larvae. I don’t have many large larvae at this time due to the crash I caused in the colony a few weeks back. I do have a lot of larvae, just not large ones yet.

fishing, bait,

Comments 7

  1. Nifty-Chicken wrote:

    Wow, that’s great!!! You could use this to test which foods they like best by timing how long / how may come to the food.

    Question: Why did they stay in the container and not leave as soon as the food was gone? Looks pretty crowded in there like they couldn’t get out (which would be good if actually trying to catch them).

    Posted 27 Jul 2008 at 1:16 pm
  2. Nifty-Chicken wrote:

    Follow up on my question: I’m wondering if you could simply dig a little hole into the compost and take a container (say a large empty container of yogurt) and place it so the top/rim is at the level of the compost. Put in some food and let the larvae crawl in but they can’t crawl out? Would that work for catching the younger ones?

    I’m also wondering if you could add small holes, say 1/6 inch, that would allow the really small ones out, but keep the bigger ones in?

    Posted 27 Jul 2008 at 1:22 pm
  3. Jerry wrote:

    Hey Nifty!

    The larvae come into the collector like the tide rises and lowers. Once they’re all in there it takes a while to find the exits. :)

    I think the yogurt container would work but I don’t know if it would be worth the extra steps. I literally just put some food in the tub and set in on the compost. 5 seconds total.

    I haven’t tried to sort the larvae for size yet. One thing to watch for is that large larvae will try to wiggle into an opening that’s too small and get stuck. (I said they were fascinating, not bright :) )

    Posted 27 Jul 2008 at 1:31 pm
  4. Nifty-Chicken wrote:

    I’ll experiment!

    Jerry, I don’t have any fish meal around. What is your top 10 list of food stuffs to tempt these guys? I think dog food is atop your list, but I don’t have this either.

    Posted 27 Jul 2008 at 1:34 pm
  5. Jerry wrote:

    I’m trying to think of something they WON’T flock to! At this very moment I’m testing plain steamed broccoli and french toast with maple syrup. So far the french toast is winning. :)

    I plan on running a series of tests to see what they’re preferences might be, but I think this method would work fairly well with most foods.

    The main reason I used fish pellets in this case is because I’m using the larvae to feed train my fish. The fish love to eat the larvae so I feed the larvae some fish pellets and also coat them with a mash made from it. That way the fish get a taste of the fish food every time they eat a larvae. I’m not sure if it will work but it seems reasonable.

    Posted 27 Jul 2008 at 1:56 pm
  6. Nifty-Chicken wrote:

    Jerry, I put out two containers, one with 1/2 side rice and 1/2 side mac-n-cheese. The other one has damp “wet cob” that is for sheep and has mashed corn, oats, and molasses?

    If I turn the soil I see a TON of BSFL but none are venturing into the container. My bin allows a tiny bit of light inside, is that the problem (they won’t venture to the surface). Does your container keep all light out? Maybe the holes in the bottom allow them to go into the container from under the ground? Maybe they just don’t like the food I’m providing.

    Looking forward to your list of best baits for BSFL!

    Posted 27 Jul 2008 at 3:43 pm
  7. Jerry wrote:

    One thing to keep in mind is that the larvae in my unit are all in a mass within 2-3 inches of the surface. Turing the compost in your traditional unit disperses the food, and therefore the larvae, throughout the unit. That’s not the case in a device specifically designed for BSFL. Even so, I think the only real difference would be that it will take longer to attract the larvae in your compost bin to the collection cup.

    My active colony is still in my old homemade unit because I’m starting my BioPod from scratch. My old box lets in quite a bit of light compared to a BioPod and I can’t be sure what kind of difference that might make. Even with the top off I can entice the larvae to the surface with new food.

    BSFL like almost all food. :)

    Posted 27 Jul 2008 at 4:18 pm

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