Bug Bucket Berlese Funnel
Materials:
1 5 gallon plastic bucket
1 12x12 inch piece of 1/4 inch hardware cloth 2 wire clothes hangers
1 14x22 inch piece of poster board 3 brass fasteners
1 600 ml beaker or jar
1 18x18 inch piece of cotton fabric 200 ml of ethanol
Tools
scissors, tin snips, box cutter, protractor, push pin, 18
inches of string and a pencil
What is a Berlese Funnel and why would you want to make this one?
A Berlese Funnel is a tool for discovering what lurks in the world beneath your feet. The leaves and decaying organic material on the forest floor are home to an unimaginable world of millions of living creatures. Much of this world is beyond our normal daily experience, but with the aid of the Berlese Funnel it is revealed.
Berlese Funnels have been used by scientists to collect arthropods for decades. The basic idea is to place a funnel beneath a sample of material and collect anything that might fall, crawl or wiggle out of the sample.
It is a very useful method when conducting broad surveys of a habitat, or when collecting very small organisms that are difficult to see or pick up.
Matrix Sample
Funnel
Collection container
Organisms fall from the matrix sample through the funnel, into the collection container.
There are a few important properties of a Berlese Funnel:
l It must be able to hold enough of the matrix sample to collect an adequate number of specimens.
l The matrix sample must be able to dry thoroughly within two to three days.
l The organisms must be able to dig through the matrix sample and fall into the funnel before they die.
This generally requires that the matrix sample be contained as a broad thin layer as opposed to a thick layer.
Step One: Preparing the bucket.
The bucket is the structure which will support the funnel. A beaker or jar will be placed below the funnel so you will need to cut an opening in the lower part of the bucket to access the beaker without disturbing the funnel and leaf litter sample.
You will need to cut an opening large enough so that you only need to tilt the breaker slightly to get it into the bucket as indicated in the illustration below. This is the hardest part of making the apparatus. There are a couple options:
1. Using a box cutter, carefully cut the square out. Cut the sides of the hole first by pushing the knife into the bucket at the upper end of one of the side cuts, then place the bucket on the floor and push the knife down toward the floor. After the two sides are cut, carefully cut the top of the opening, then the bottom. The top and bottom cuts are tricky because the bucket tends to roll. Don't cut towards yourself or anyone helping you, if you should slip you could cut yourself or your helper.
2. Another technique is to heat an old dinner knife in the flame of a stove or Bunsen burner. Then press the hot knife into the bucket, it should melt through the bucket as you cut along the desired line. You will have to return to the flame to reheat the knife several times as you cut. Be very careful not to touch the hot knife!
3. A third option is to use a keyhole saw, but getting the cut started is the tricky part.
In the end you should have a bucket with a hole cut in the side as shown. You will need to be able to place the beaker, about 1/3 full of liquid, into the bucket without spilling (too much).
1 2
3
4
Making the funnel:
String
Poster Board
Push Pin
205 degrees
10.25"
2.5 "
1) Tie a piece of string to a push pin.
2) Tie a pencil with the string so that when the string is taut the distance between the pin and the pencil point is 10 1/4 inches.
3) Place the poster board on top of a sheet of corrugated card board and push the pin into the board as indicated in the illustration to the left.
4) Trace out an arc with a 10 1/4 inch radius as shown.
5) Repeat the process to draw another arc with a 2 1/2 inch radius.
6) Draw a straight line from where the push pin was to the outer arc as shown by line "A."
A
B 7) Using a protractor measure 205
degrees from line "A" and draw line "B" at this angle.
8) Following the lines that you have drawn,
fastener
Adjusting the Funnel
Place an empty beaker in the bucket.
Insert the paper clipped funnel into the bucket.
Adjust the diameter of the funnel until it hangs just above or even with the top of the beaker.
Remove the funnel and use three brass fasteners to fix the funnel at this diameter.
Making the Screen:
Place the funnel on the hardware cloth as shown in figure 1.
Trace around the base of the funnel with a marker.
Using the tin snips cut out the traced circle.
Figure 1.
Cut the two hangers as indicated below.
Heat the straight end in a candle flame or on a stove top and make four holes in the bucket as indicated by the black arrows in figure 3.
Masking tape
Light cotton sheet
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Setting up the Funnel
Leaf Litter
Place leaf litter on top of the screen in bucket as shown.
Cover the top of the bucket with cloth and use masking tape to hold it in place.
Place beaker with 70%
ethanol below funnel and turn on lamp above the bucket to accelerate the drying of the leaf litter.
Can you figure out how to collect the specimens live?
After a few days, remove the beaker and examine the contents. You should find a wide variety leaf liter arthropods. You will be able to see some of your specimens with the unaided eye, others you will need a magnifying glass or a dissecting microscope to help you identify them.
l Sort them into vials by group (spiders, ants, beetles, centipedes, millipedes...).
l Which are the most common? Why?
l Which ones feed on other invertebrates and which feed on plants or fungi?
How do you know? How could you find out?
l If you collect samples during different times of the year do you see different organisms?
Can you think of questions that you could answer with this tool?
When you look at your specimens do any new questions come to mind?
