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Activity: Pitfall Trapping
Purpose: To catch animals that crawl through the leaf litter. These traps are usually left for several days allowing for the capture of nocturnal animals.
Materials (per trap):
- 2 plastic disposable drinking cups
- Piece of thin wood or particle board, approximately 12 cm x 12 cm
- Small amount of propylene glycol (“safe” antifreeze), about 25 ml
- Trowel or bulb planter
Procedure:
- Remove leaf litter from a small area. Dig a hole just big enough for the cups, one nested inside of the other. Leave the top edge of the cups level with the soil.
- Pour about 2 cm of propylene glycol into the cup.
- Lay the piece of wood over the cup, with sticks, rocks, or nails under the corners to hold this cover up about ¼" above the cup. (The purpose of the cover is to keep small mammals out of your traps.) Put a
stick or stone on top of the cover to hold it in place. Redistribute the litter around the trap.
- Leave traps for a few days.
- Collect specimens from the traps by pouring the propylene glycol through a tea strainer or pick animals out with forceps.
- Store collected animals in alcohol. Be sure to label your container.
- Identify and count animals.
- Return collected animals to clean alcohol for storage.
Placement and number of traps:
One recommended protocol (Albert T. Finnamore Curator of Invertebrate Zoology at the Provincial Museum of Alberta) for obtaining 85% of the arthropods possible to trap in pitfalls is to set up 8 to 10 traps in a 10-meter circle. Thus, one could place the tree in the center of the circle, with 8 to 10 traps spaced evenly in a circle five meters out from the tree. 
Tip
: Do not thoroughly hide your traps. You may not be able to find them again! Either leave the cover free of litter or flag your traps.
Tip: Traditional antifreeze is good tasting to dogs and will kill them if they drink it. Therefore, use the newer, safer antifreeze containing propylene glycol. An
alternative is to use a mixture of water, salt and detergent. The salt will act as a preservative and the detergent (unscented) will break the surface tension so that the arthropods will sink and drown.
Tip: Cardboard will not work as a trap cover. It will absorb moisture, come apart, and warp.
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