Entomology 311 Lab Manual - 1st Edition, 2019

E. Pitfall Trap
There are many nocturnal arthropods that are difficult to spot
and capture either because they aren’t out during daytime
sampling activities or because they are difficult to see in the dark
when they are active. Additionally, many ground-crawling
arthropods are difficult to sample in general without devoting a
great deal of time to searching. For these, pitfall traps are useful
for sustained sampling without a great deal of effort (figure 1-5).
Pitfall traps are simple to construct: a cup is placed into a hole
dug in the ground, with the top edge of the cup level and in
contact with the soil surface (not above – this may act as a barrier
and discourage insects from walking into the trap). Insects that
wander into the trap fall into the cup where they are trapped until
the pitfall is recovered by the collector. For live catch, a deep, dry
cup is ideal to prevent escape. If the arthropods need not be live,
then 1-2” of water in the bottom of the cup with a few drops of
soap to break the surface tension will ensure none escape. If water
and soap is used, it is important that the trap be out no longer than
24 hours before recovery to prevent the insect bodies from
breaking down in the solution. If the trap needs to be out for a
longer period, a preservative should be used to prevent this from
happening. Recreational Vehicle (RV) antifreeze containing
Figure 1-5: Pitfall traps are ideal for collection
nocturnal and ground crawling species. Image
source: https://commons.wikimedia.org/w/
index.php?title=File:Barber_pitfall_trap.jpg&o
ldid=269026568
propylene glycol evaporates slowly, can be reused and is reasonably environmentally safe for such needs. To
protect captured insects and arthropods from birds, rodents and rain, it is also suggested to place some kind
of cover over the pitfall trap, leaving at least 2” of space between the ground and the cover.
12 | Week 1: Reading