Lesson #6: Sifting trays

>> Sorting of pupae and larvae and sieving of frass are essential parts of the mealworm rearing process.

After some time, we will realize that providing for the insects’ basic needs is not that time-consuming. What really occupies us, on the other hand, are various sorting tasks we encounter. Now let’s take a look at how to handle this as efficiently as possible and, most importantly, what tools we need for it.

Manual sorting

The easiest option suitable for beginners is to buy a set of all the necessary screens specially designed for breeding mealworms, for example, from the company LarveMe.

For beginners – sieve set LarveMe

The LarveMe sieve set includes all the necessary sieves.

mealworm sifter ofera

Mealworm sorting

It’s relatively expensive, but since I couldn’t find a cheaper option on the internet after establishing my farm, I was quite happy to get it a few weeks after exhausting manual sorting. Its advantage is good compactness, the sieves are not too large, but this comes at the cost of more laborious sorting tasks. For example, you can’t sort larvae and sift frass at the same time, as other sorting sets allow. Therefore, it is suitable only for small-scale production – if you have just a few breeding boxes.

Sorting Machines

Let’s go to the other extreme. If you have a large mealworm farm that’s already profitable, you can make your life easier with a sorting machine that can perform nearly miraculous tasks. There are Chinese products available on the internet, priced at around 4 K€, and European variants can be several times more expensive. You can see what such a sorting machine looks like in action, for example, in this video.

mealworm automatic sorting
For professionals – automatic sorting machine

It sorts grown larvae from small ones, as well as impurities and frass from the container.

For someone who sorts manually, it’s truly a spectacle, yet I guess that most of us, due to financial and space constraints, will only swallow dryly and forget it.

Mealworm sifting trays Insecto

The optimal middle way – the third option. If we are no longer beginners, enjoy mealworm farming, and want to advance our production by a few nice kilos per month, small circular sieves will definitely not be sufficient.

The good news is that with the right hardware, we can separate pupae, grown-up larvae, small larvae and frass from each other with relatively little effort, all in one single step.

Online shop – sifting trays Insecto

All sorting tasks can be performed in one single step at once – instructional video included.

mealworm sorting of pupae and larvae

Mealworm sorting

For this purpose, we will construct a sorting tower with three sieves. At the top, a sieve for pupae (3.5 mm mesh), in the middle, a sieve for harvesting (2.5 mm mesh), and at the bottom, a sieve for sifting frass (0.5 mm mesh). Under the tower, we will place a container for collecting frass, preferably some closed one, to reduce dust during sorting.

The entire content of the breeding box intended for sorting is poured into the top section of the tower. The top sieve is the coarsest and allows everything except for pupae to pass through. In the second sieve, larger larvae suitable for pupation or harvesting will get caught. Only frass will pass through the third sieve, with smaller larvae and substrate residues remaining in it. The sorting system can be left to stand still for some time. Mealworms will sort themselves with their movements, or you can accelerate the process with circular motion. The sorting will certainly not be perfect and will require some manual re-sorting. But it will only take a few extra minutes. Especially in the middle sieve, a few larvae overestimate their waistline and get stuck.

One issue is the homemade production of such sieves. It’s not a big challenge for the average handyman, but for someone like me – making them was quite a workout. So, if you’re not a DIY enthusiast, you might prefer to purchase a some sorting set for a reasonable price from an online store.

Sorting living / non-living

The last issue is separating impurities and dead insects from the harvested larvae. If we grind the substrate finely enough and maintain cleanliness with few foreign impurities, we can perform the sorting manually. However, when, for instance, the substrate contains a high amount of poorly ground cereal grains, these can gradually accumulate and be challenging to sort.

To separate impurities, a method similar to sorting beetles from pupae can be employed. Place damp paper over the box, and the hungry larvae will cling to it. After a few minutes, gently shake them into another container. The second method involves pouring the mixture to be sorted onto an egg carton and flipping it over. Whatever remains attached is alive, and it can be shaken into a different container again. Yes, both methods are somewhat labor-intensive and not 100% effective. You have to repeat both processes tirelessly, but I haven’t found a better “non-device” alternative.

I discovered an interesting method in a video from a Korean farm. This sorting principle leverages the larvae’s instinct to escape from the reach of light and warm. It’s a bit time-consuming as you need to keep the light on for 1-2 hours, but I tried it on an improvised setup, and it works quite well.

Sorting by Light

The process of rearing mealworms, Korean-style. Sorting living from non-living using a light bulb begins at the second minute of the video.

Korean light sorting

Unfortunately, no matter what method or automatic machine we use to sort the living from the non-living, we must accept that it will never be 100% effective. Resting larvae before pupation and pupae will always end up among the impurities, requiring manual re-sorting.

Mealworms in the kitchen >>

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