You can make your own Berlese-Tullgren specimen collection funnels using a standard two-liter bottle. Berlese-Tullgren funnels are often used by scientists to collect spiders and insects from debris samples taken from their natural habitats. The funnels capture specimens and preserve them in a chemical solution until they can be closely examined. Berlese-Tullgren funnels are very effective and may catch multiple specimens from a single sample. Build an inexpensive funnel trap to explore the spiders and insects that live in your environment.
- Skill level:
Things you need
- 2-liter bottles
- Permanent marker
- Utility knife
- Petri dishes
- Anti-freeze or isopropyl alcohol (70%)
- Duct tape
- Galvanised hardware cloth or wire mesh wire mesh (1/4-inch grid)
- Wire cutters or tin snips
- Lawn litter (decomposing yard waste, needles and leaves)
Set the two-liter bottles upright on their bases and measure five-and-a-half inches up the sides of the bottles from the surface. Mark the measured points with a permanent marker. Hold the marker in place on the mark and slowly spin the bottle on its base to draw an even line all the way around.
Push the blade of a utility knife into the side of each bottle and follow the marker guidelines as you spin the bottles to cut them all in half. Unscrew and discard all bottle caps.
Place a petri dish inside the base of each halved two-liter bottle. Fill the dishes half full of automotive antifreeze or isopropyl alcohol.
Invert the severed top portions of the bottles so that the mouths of the bottles face down. Lower the tops into the bases. Tape the cut rims of the two halves together so the mouths of the bottles are resting no more than an inch above the preservation liquid.
Cut a four-inch square out of the hardware cloth using a pair of wire cutters or tins snips for each bottle. Bend an inch of each corner on all the squares with a pair of pliers so that the bent points stick straight out. Lower the mesh squares into the inverted top halves of the bottle with the bent points facing down.
Collect lawn litter from underneath bushes and trees. You need about two cups of decomposing plant material and dirt to fill each Berlese-Tullgren funnel. Loosely sprinkle the yard material into the top part of the funnels and break apart any clumps of organic material.
Set the loaded Berlese-Tullgren funnels under a 25 or 40-watt lamp and wait for twenty-four hours for the lawn material to dry out completely. Remove and discard the dry material. Peal away the tape holding the two sections of the funnel together and lift out the top section so the specimens can be collected.
Tips and warnings
- Refill and reuse Berlese-Tullgren funnels until they are too damaged to function properly.
- Some insects and spiders may still be alive and caught in the lip of the bottle when you pull the two halves apart.
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