I recently decided to make a Berlese-Tullgren funnel so that I can collect more litter critters, particularly Myriapods. My typical collecting method is hand collecting with a claw to swipe back leaf litter and move logs, which has worked very well for finding large millipedes and centipedes. I also use an aspirator to collect stone centipedes (Lithobiomorpha), which ensures they don’t drop their ultimate legs like they do if you try to grab them with forceps. This has worked out great, but these methods rely on active collection and being able to see the specimens myself, which means I’m missing out on the more cryptic critters like symphylans and pauropods. The magic of the Berlese-Tullgren funnel is that it’s a passive method and can extract many more arthropods from a leaf litter sample than I can collect myself in the same period of time. Plus, it should extract specimens I would definitely miss by just hand collecting.
A Berlese-Tullgren funnel is a simple design. Starting from the bottom, you have a collection container (a cup, bottle, etc.) filled with a preservative (alcohol or propylene glycol). Suspended above the container is a funnel with a mesh, on top of which leaf litter or soil is placed (typically it is sifted in the field before being placed in the funnel to increase extraction efficiency). On top of this funnel is a heat source (typically a light bulb) that drives the arthropods down through the mesh by the desiccation gradient induced by the heat source. After falling through the funnel, the arthropods end up in the collection container and can later be removed for study. A litter sample is typically left in the trap for at least 48 hours, but this time can vary.
However, a Berlese-Tullgren funnel also costs much more than my $8 collecting claw. The current price of one from Bioquip is $108 (https://www.bioquip.com/search/DispProduct.asp?pid=2831), which is more than I wanted to pay. It’s a fine trap, though a bit small, and I don’t like the design of the lid. Carolina Biological sells an even smaller version for $28 (https://www.carolina.com/entomology/berlese-funnel/654148.pr), but it looks more suited to classroom demonstrations rather than more serious uses. Since neither of these fit my needs, I set off to make my own.
My main goals were to be able to extract a large amount of leaf litter with each run, make it relatively portable, and to keep it cheap--hopefully around $50 or so in materials, so I tracked how much I was spending on supplies. There are a number of scientific papers published about Berlese-Tullgren funnel designs, though I didn’t find them very helpful for actually constructing one and figuring out the exact cost. If you’re interested in extracting a particular group of arthropods with your funnel, I recommend that you consult the literature for trap comparison and efficacy papers for your group. With a cursory internet search, I found this nice design (https://www.instructables.com/Berlese-Funnel/) by Tucker Lancaster from about 10 years ago, which is probably cheaper than my design. If you have any of the same materials already like he did, it might work well for you.
One of the biggest hurdles to making my own Berlese-Tullgren funnel was simply knowing the name of each piece, since I was cobbling together various items and visiting different stores. It’s a bit difficult to bridge the lingo gap with the hardware store employee sometimes, but they were always very helpful. It was also tough to find the right search terms online, so I’ll include what I used for each item. I ended up making two Berlese-Tullgren funnels with slightly different designs, and I’ll detail the costs of each. My base design needed the following:
1 five-gallon bucket
1 funnel
1 clamp light (also marketed as a heat lamp)
1 metal mesh
1 light bulb
1 cup
Supplies for Design 1: a five-gallon bucket with hole cut out from the side, a large plastic funnel, a clamp light, an empty yogurt cup, and a garden soil sifter.
The five-gallon bucket was the easiest item to find, and cheaper than I expected! I got mine at Home Depot for $3.98. The bucket is about 14.5 inches (36.8 cm) tall and 12 inches (30.4 cm) wide, which I prefer over the stouter buckets they also sell. You want a bit more height to accommodate the funnel inside the bucket, as well as the cup you’ll place on the bottom. You will also need to cut a hole in the side of the bucket so you can easily replace the collection container. You can cut a hole with a rotary tool or power tool with a saw attachment; I had a friend help me out with this. It can be easier to do if you drill a series of holes to outline the hole, then cut through those. Be sure to wear eye protection and take typical safety precautions, just in case. Five-gallon buckets are pretty thin, and shouldn’t be too difficult to cut. I kept the cut out pieces from my buckets and lean them against the traps while they’re running so I can convince myself they’re still useful and keeping any escaped arthropods inside the bucket, rather than pieces of trash to be discarded.
Design 1: assembled with funnel and collection cup inside bucket, garden soil sifter sitting inside funnel.
The funnel for trap design 1 was more difficult to get. I tried searching a few hardware and home improvement stores, as well as department stores, but the funnels I found were much too small. I eventually found a perfect funnel from a beer home-brewing company (https://www.morebeer.com/products/funnel-12-diam.html). It’s 12 inches (30.4 cm) in diameter and 11.25 inches (28.6 cm) tall, and the funnel and fits perfectly in the five-gallon bucket. It cost $12.99 plus shipping, which ran me a total of $21.67. As an alternative, you may be able to use tractor funnels, which I assume you can find at tractor supply stores.
Plastic funnel with author for scale.
The clamp light was another easy to find item, and may also be sold in stores as a heat lamp. I believe they’re typically used by people hatching chicken eggs and such. You can buy them at local hardware stores or even big box stores, though dimensions vary. My smaller lamp is 10.375 inches (26.35 cm) in diameter, and sits slightly within the funnel. It cost $11.57, cheaper than expected. I also bought another one marketed as a “heavy duty heat lamp” with the same diameter, though it’s slightly taller and more domed; it cost me $13.
Trap design 1 fully assembled with bucket contents and clamp light on top.
Getting the metal mesh gave me the most trouble. You may have an easier time with this part, depending on what tools you have available. It’s often recommended to use ¼ inch (0.64 cm) hardware cloth for your mesh, and this can work great! You can find it at hardware stores for about $8, but they sell it in large quantities. For my purposes, I only needed an ~8 inch (20 cm) disc, and I didn’t have the tools to cut it. To try to simplify the process, I opted for a mesh substitute. It took a while to find something with the correct mesh size, and to figure out the best search terms to use online. “Soil sifter” and “sifting pan” gave me the best results, but you might also try “mesh sieve” or “soil sieve.” I couldn’t find anything in stores that matched what I needed, but if you have a specialty garden store nearby, they might be able to help you. I had better results searching online, and eventually found what I needed, which was marketed as a soil sifter (https://www.amazon.com/dp/B08B8JQZH4) and sold for $15.99 plus shipping (total of $23.15). It’s 7.8 inches (19.8 cm) in diameter and has 0.39 inch (1 cm) diameter holes, a bit larger than the typically recommended ¼ inch (0.64 cm) holes. I’ve found it works just fine though, and it sits nicely within the beer funnel. The clamp light fits entirely around it, enclosing all the litter, preventing escapees.
Top view of trap design 1, with soil sifter inside funnel.
Top view of trap design 1, with leaf litter.
For trap design 2, I bought a stackable sifting pan (https://www.amazon.com/dp/B008B0T5Z2) which is marketed for people panning for gold. It’s 13.25 inches (33.65 cm) in diameter and has the typical ¼ inch (0.64 cm) mesh. It was a bit pricier, and cost me $31.58 ($29.99 + tax, but I got free shipping with it). It fits on top of the five-gallon bucket and has a rim, which came in handy later. The sifting pan can fit more litter than the smaller soil sifter (which has metal sides enclosing the litter), and I bought a pack of wooden paint stirrers for $1 at Home Depot to place on the rims. This way, I can elevate the clamp light above all the litter, rather than placing it directly on the litter pile. The clamp light doesn’t enclose all the litter like on the other Berlese-Tullgren funnel, but that hasn’t been a problem so far. If your target arthropods are apt to crawl or fly out of the litter while it’s sitting in the funnel, you might have to fiddle with the design a bit so you don’t lose them.
Trap design 2, with sifting pan set up on top of the bucket.
Now, with trap design 2, I couldn’t fit a large funnel onto the bucket like with design 1. The sifting pan was already on top of the bucket, and didn’t fit snugly into the same funnel. Instead, I got a garbage bag and cut out the bottom, and then cut the corner of the bag. Next, I took a large rubber band and attached the bag to the bottom of the sifting pan, creating a make-shift funnel. This worked fine, but I had an extra 6 inch (15 cm) diameter plastic funnel lying around, so I put this into the cut garbage bag, which made it sturdier. It also made the process cleaner, as detritus and/or specimens can escape the bag without the funnel there.
Trap design 2, showing sifting pan with garbage bag and smaller funnel inside.
Trap design 2, top view showing sifting pan mesh and funnel below.
Trap design 2, fully assembled.
The light bulb was simple and fits right into the clamp lights. I got a two pack of 40W replacement bulbs that only use 29W and are marketed as Eco incandescent bulbs. I’m not sure how these differ from the normal incandescent bulbs that have been phased out in recent years, but they still give off a good amount of heat to help drive arthropods down through the mesh. They’re A19 bulbs, which are the typical bulbs used for lamps.
For the collection container, I use plastic yogurt cups (after I’ve eaten the yogurt). They fit right under the tip of the funnel, so any arthropods that fall through don’t have room to escape before they fall into the preservative. I’ve tried a few different preservatives so far. I bought a gallon of RV antifreeze, which is about 60% water, 30% propylene glycol (which is non-toxic, rather than ethylene glycol), and 10% miscellaneous additives. It’s a pleasing pink color, but tends to make specimens too floppy for my liking. I tend to use 70% isopropanol (rubbing alcohol) instead, which preserves specimens well and has a good balance on the rigid-floppy scale. If you’re interested in preserving specimens for genetic sequencing, however, you should use either 95% ethanol or 95%+ propylene glycol. Molecular grade ethanol is tough to get if you’re not affiliated with a university, but high percentage propylene glycol seems to be more readily accessible, and doesn’t have the same shipping concerns as ethanol. Isopropanol is readily available at grocery stores and pharmacies for as little as $2 a bottle, though it has been more difficult to find during the pandemic. Whichever preservative you use, check the collection container after a few days and refill it as necessary, as it will evaporate over time.
Berleseate in collection cup. This sample came from a rhododendron grove and had some rare centipedes in it, a great haul!
Now it’s time to compare the total price for both Berlese-Tullgren funnel designs. For the first design, it had four main components:
Items Price
Soil sifter 23.15
Funnel 21.67
Bucket 3.98
Clamp light 11.57
Total $60.37
Shipping costs for the soil sifter and funnel ($15) made this one slightly more expensive, with a total cost of $60.37.
For the second design, it only had three main components, plus the paint stirrers to support the clamp light:
Items Price
Sifting pan 31.58
Bucket 3.98
Clamp light 13
Wooden paint stirrers 1
Total $49.56
Shipping was free for the sifting pan, and I didn’t need a large funnel for this one, so it ended up being cheaper, with a total cost of $49.56. This cost doesn’t include the rubber band, extra funnel, and garbage bag though, so you may need to buy some of those items.
My aim was to keep the cost of my homemade Berlese-Tullgren funnel around $50, and I was able to stick to that budget. I could have bought one trap from Bioquip for the amount I spent on these two, and now I can extract twice the amount of litter! My traps can also extract a larger volume than the Bioquip traps (though design 2 with the sifting pan can extract much more than design 1). The traps are portable, rather than bolted to a shelf, which is another nice bonus. (Of course, the Bioquip traps are also nice and portable.)
So that’s the flat cost of my two Berlese-Tullgren funnels. You’ll also incur some additional expenses as you run them. I didn’t include the cost of preservative ($2-$5 for isopropanol or RV antifreeze) or the cost of the light bulbs (~$2 each). I also didn’t include a cost for the collection containers, as any sort of cup-like object should work fine.
To collect my litter samples, I use a litter concentrator (aka litter reducer) to sift piles of leaf litter in the field. Bioquip sells one for $440 (!!!!!!!!) (https://bioquipinc.com/catalog/collecting-equipment-supplies/litter-reducer/), but Paradox Company, based in Czechia, sells one for 58 euro (http://www.insectnet.eu/field_equipment.php#sita_entomologiczne). I use theirs (the model with the 1 cm mesh) and it has held up for almost a decade now. You can also make your own—a colleague of mine uses a cat litter box with the bottom cut out and replaced with hardware cloth. Once you’ve sifted enough leaf litter, place the litter into a bag for transport. I used to use gallon-size plastic bags, but now use old pillow cases instead. I bought three from a local thrift store for 50 cents each, what a deal! Just make sure you don’t let the bags overheat after you’ve collected them, or you might cook your arthropods before you transfer them.
Pillowcase for leaf litter transport, with litter.
You’ll also need a microscope (and light source!) and some kind of dish to examine your samples in after you’ve run the traps. Transferring the specimens from the collection container can be made slightly easier by pouring the sample through multiple tea strainers (one with a closer mesh size, one with a larger mesh size to separate the smaller and larger specimens and detritus), which might cost you somewhere in the neighborhood of four bucks. There’s also the associated vials to house your specimens and extra alcohol costs, but that’s going down the rabbit hole. Suffice to say, there will be additional costs after you’ve set up the Berlese-Tullgren funnels to begin with. But setting up the trap itself will cost you about $50 with my designs.
I’ve been quite pleased with the arthropods from my samples so far. I’ve found a few centipede and millipede species I missed by hand collecting, and I’ve also gotten a fair number of pauropods and symphylans, which I rarely am able to collect by hand. I still do some hand collecting, but I make sure to grab a few bags of leaf litter for my traps while I’m out too.
Collage of specimens I’ve collected with my trap designs. Standouts include Eurypauropus pauropods, Garibius centipedes, Anillinus ground beetles, Erebomaster harvesters, Strumigenys and Stigmatomma pallipes ants, Striaria millipedes, and Dasycerus beetles.
I haven’t noticed any differences between the two designs in terms of what arthropods I get, so the size difference between the two meshes doesn’t seem to have an effect. The first design can’t handle as much litter, so I probably get fewer arthropods, though it does dry out the sample quicker. I may eventually cut the side rim off the soil sifter to increase the volume of litter I can fit in it.
For any of you looking to put together your own Berlese-Tullgren funnel, I hope this has been helpful. If you have your own design or improvements to mine to share, please let me know! There’s lots of great litter critters out there, and the more people we have searching, the more surprising discoveries we can make. When it comes to myriapods in particular, we can definitely benefit from having more people searching to fill in distribution gaps. If you get myriapods but aren’t going to do anything with them, contact me and I’ll gladly take them off your hands!
Finally, I want to give a special thanks to the Means family for helping me cut my buckets and for critical design input!
Update (11 Oct 2021): Tom Sheehan brought an interesting article to my attention about making a $3 Winkler sampler—if you prefer those over the Berlese-Tullgren funnel, you can check it out here. I also added the citation below.
Further reading:
Other Berlese-Tullgren funnel designs:
Barberena-Arias, M. F., González, G., & Cuevas, E. (2012). Quantifying variation of soil arthropods using different sampling protocols: is diversity affected. Tropical Forest. InTech Online Publisher, www.intechopen.com, 51-70. https://www.fs.usda.gov/treesearch/pubs/download/40532.pdf
Brown, R. D. (1973). Funnel for extraction of leaf litter organisms. Annals of the Entomological Society of America, 66(2), 485-486. https://doi.org/10.1093/aesa/66.2.485
Crossley Jr, D. A., & Blair, J. M. (1991). A high-efficiency,“low-technology” Tullgren-type extractor for soil microarthropods. Agriculture, Ecosystems & Environment, 34(1-4), 187-192. https://doi.org/10.1016/0167-8809(91)90104-6
Kamczyc, J., Pers-Kamczyc, E., Urbanowski, C. K., Malica, J., Reich, P. B., & Oleksyn, J. (2020). An alternative, portable method for extracting microarthropods from forest soil. Acta Oecologica, 109, 103655. https://doi.org/10.1016/j.actao.2020.103655
Tuf, I. H., & Tvardík, D. (2005). Heat-extractor–indispensable tool for soil zoological studies. Contributions to Soil Zoology in Central Europe I. Institute of Soil Biology, ASCR, České Budějovice, 191-194. https://www.researchgate.net/profile/Ivan-Tuf/publication/228496919_Heat-extractor-an_indispensable_tool_for_soil_zoological_studies/links/0c960532a7b75a66c4000000/Heat-extractor-an-indispensable-tool-for-soil-zoological-studies.pdf
Williams Jr, E. C. (1953). A Modified Berlese Funnel. In Proceedings of the Indiana Academy of Science (Vol. 63, pp. 163-164). https://journals.iupui.edu/index.php/ias/article/download/5977/5996
Similar leaf litter traps:
Besuchet, C., Burckhardt, D. H., & Löbl, I. (1987). The" Winkler/Moczarski" eclector as an efficient extractor for fungus and litter Coleoptera. The Coleopterists' Bulletin, 392-394. https://www.jstor.org/stable/4008527
Ferro, M. L. 2018. A $3 Homemade Winkler Sampler. Hamuli. Newsletter of the International Society of Hymenopterists 9(1): 5–6.
Grebennikov, V. V. (2016). High-output suspended mega-sifter for sampling forest litter mesofauna. Fragmenta entomologica, 48(2), 123-124. https://www.readcube.com/articles/10.4081%2Ffe.2016.183
Owens, B. E., & Carlton, C. E. (2015). " Berlese vs. Winkler": Comparison of Two Forest Litter Coleoptera Extraction Methods and the ECOLI (Extraction of Coleoptera in Litter) Protocol. The Coleopterists Bulletin, 645-661. https://www.jstor.org/stable/24773669
Wheeler, Q. D., & McHugh, J. V. (1987). A portable and convertible" Moczarski/Tullgren" extractor for fungus and litter Coleoptera. The Coleopterists' Bulletin, 9-12. https://www.jstor.org/stable/4008312
Propylene glycol as a preservative for DNA:
Ferro, M. L., & Park, J. S. (2013). Effect of propylene glycol concentration on mid-term DNA preservation of Coleoptera. The Coleopterists Bulletin, 67(4), 581-586. https://doi.org/10.1649/0010-065X-67.4.581
Moreau, C. S., Wray, B. D., Czekanski-Moir, J. E., & Rubin, B. E. (2013). DNA preservation: a test of commonly used preservatives for insects. Invertebrate systematics, 27(1), 81-86. http://dx.doi.org/10.1071/IS12067
Nakamura, S., Tamura, S., Taki, H., & Shoda‐Kagaya, E. (2020). Propylene glycol: a promising preservative for insects, comparable to ethanol, from trapping to DNA analysis. Entomologia Experimentalis et Applicata, 168(2), 158-165. https://doi.org/10.1111/eea.12876
Steininger, S., Storer, C., Hulcr, J., & Lucky, A. (2015). Alternative preservatives of insect DNA for citizen science and other low-cost applications. Invertebrate Systematics, 29(5), 468-472. http://dx.doi.org/10.1071/IS15003
Weigand, A. M., Desquiotz, N., Weigand, H., & Szucsich, N. (2021). Application of propylene glycol in DNA-based studies of invertebrates. Metabarcoding and Metagenomics, 5, e57278. https://doi.org/10.3897/mbmg.5.57278