Pitfall traps should be serviced at least once a week.
To service a circular trap:
- Remove the plywood cover.
- Lift the collecting cup out of the permanent cup, disturbing the permanent cup as little as possible.
- Pour contents of the collecting cup through a household strainer or fine wire mesh screen supported by a funnel into an empty collecting cup.
- Empty contents of the screen into a specimen cup (4-ounce size works well) containing 70 percent ethyl alcohol. Swish the screen in alcohol to remove remaining contents, then rinse the empty collecting cup, screen, and funnel using a spray bottle of water.
- Secure the lid on the specimen cup for transport.
- Place the collecting cup back into the permanent cup. Build up soil around the collecting cup so that no gaps exist between cup and soil, and replace debris if needed.
- Add killing/preserving agent so there are 1 to 2 inches of fluid in the collecting cup.
- Reinstall the plywood cover.
To service a barrier trap:
Both pitfall traps that comprise a barrier trap can be serviced at the same time by pouring the contents of one collecting cup into the other, then following the steps for servicing a circular trap. When reinstalling collecting cups, make sure both cups receive 1 to 2 inches of fluid.
Specimen Processing:
Collected specimens can be stored in 70 percent ethyl alcohol or pinned for dry storage and identification.
Comments and Tips:
- In rainy conditions, mounding the soil so that the trap is just slightly higher than the surrounding soil surface will help reduce “flooding” of the cups.
- If a collecting cup fills with rainwater, dump it out and replace with fresh killing/preserving agent.
- Small animals sometimes get caught in traps.
Remove toads, mice, worms, slugs, etc. before collecting arthropods. A funnel wedged into the top of the collecting cup will help prevent some small animals from falling into the trap.
- Make sure lids on the specimen cups are secure so that alcohol does not spill out or evaporate.
- Label specimen cups with field name, date, and trap number if necessary.
How Many Traps per Site?
Install at least three traps per site, and more if you have time to sample them. Space traps at least 20 feet apart so that traps don’t ‘compete’ with each other.
More about Killing/Preserving Agents
In cooler, moist conditions or if the traps are serviced often (more than once a week), salty water with a few drops of liquid soap can be used. However, when servicing traps that use soapy water, specimens should be rinsed in fresh water before being transferred to alcohol to prevent a film from forming on the specimens.
Evaporation of this water-based solution may be a problem in hot weather. In drier, hotter conditions or if traps are serviced less often than once a week, a solution that evaporates slowly should be used.
Automotive antifreeze has a low rate of evaporation and will remain in pitfall traps for a long period of time. However, most brands of antifreeze should not be used because they contain about 95 percent ethylene glycol, which is deadly poisonous.
This compound tastes sweet and is attractive to pets and other animals. When ingested even in very small quantities, ethylene glycol causes kidney failure and death. “Pet-safe” antifreezes contain propylene glycol, which is much less toxic than ethylene glycol. A 50/50 mix of pet-safe antifreeze and ethyl alcohol or water works well.
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