Tierra de Oro Laboratory

Physiology and Ecology in the Pinyon-Juniper Savannah

Tag: seasons

  • Setting Up Pitfall Traps for Beetle Surveys in 2025

    Starting surveys for 2025

    Photo of grassland with a small cholla cactus in the center foreground, small juniper and pinyon on the right side, and larger junipers in the background. Small blue flags are located at regular intervals.
    Trap location, looking northeast. Small blue flags remain in place to mark locations of traps. One trap, with a painted cover held down by a rock, can be seen in front of the cholla cactus. 3/3/25.

    Inspired by comments from my friend and colleague Dr. Drew Talley, and conversations with a local Master Gardener, we set up a small array of pitfall traps to collect and record beetles over the course of the year.

    It is a 3 X 3 grid, so nine traps total, spaced 3 meters apart. We set out flags to mark the locations of the traps in a section of the back acre of the lab where foot traffic was minimal.

    Blue plastic cup buried in red sand surrounded by grasses.
    Pitfall trap, consisting of a plastic cup buried to the rim . Note that the rim is flush with the soil. 3/4/25.

    The traps are plastic party cups, buried to the rim. The soil is quite loose, so placing the traps was easy.

    Painted wooden square, with legs partially buried in soil. Rock on top.
    Pitfall trap with plywood cover. Legs are partially buried, leaving space for entry of beetles. 3/4/25

    Once the traps were in place, we put plywood covers over them to keep debris out and shield any animals that fall in.

    Plywood covers with wooden legs, unpainted.
    Plywood covers for pitfall traps before painting. Covers are 6 X 6 pieces of plywood with 3/4 wooden dowels screwed into place.

    The covers are 6″ X 6″ pieces of plywood, each with three legs made from 3/4″ dowels. The 3″ legs allow them to be partially buried for stability. Once screwed together they were given a few coats of latex paint to protect them from the elements.

    We’ll set traps for the first week of each month, for five nights at a time.

    I have not seen beetles in the neighborhood before April, so it is unlikely any will fall into the traps this month. Knowing when beetles are not active provides an important baseline for when they first appear.