Field Science Challenge #2 – Mystery Critters in our Midst

Have you ever considered what the world would look like if dead things did not decompose?  Imagine piles of leaves on the ground that never go away.  Or, maybe this is a grosser thought, but imagine the bodies of animals – mice, deer, foxes, etc. just laying around after they die.  Have you ever looked closely at an animal body as it begins to decay?  Who are the types of creatures that eat rotting animal flesh and recycle its nutrients back into the soil?  Many are not even visible to the human eye, but some of these decomposers are big enough to see, especially carrion beetles.  Carrion beetles are the mystery critters we’re going to capture.  At RMBL, we have multiple research projects studying a type of carrion beetle known as burying beetles (Nicrophorous species).  These beetles find the carcasses of small mammals to bury and then lay their eggs around the carcass so that the larvae can feed from the flesh of the dead animal.  You can watch each phase of the beetles’ life cycles take place when you place a male and female burying beetle in captivity with a dead mouse!  For our field challenge, we’re just going to focus on catching some adult beetles.

Recorded Lab Chat with Dr. Rosemary Smith

What We’d Like to Find Out: Can you attract burying beetles in your neighborhood with a simple trap?
How many different species are present?  Do burying beetles appear more often in certain habitats than others?

What You’ll Need: You’re going to build a homemade beetle trap! You can do just one trap or set up multiple traps with the materials listed below (with more you’ll have a better chance of seeing something, and you can compare differences between trap locations too!)

• A notebook and pencil or something to write with (to record your observations)
• An empty sturdy container of some kind that is between 15cm to 30cm tall and between 10cm and 30cm wide (eg a metal number 10 food can or coffee can works great; you can also use a plastic container such as a milk carton with the top cut off)
• Poke at least three pencil sized holes in the bottom of this container to help drain water
• A stake, a fence post, or a tree branch where you can attach the can about 1 meter off the ground near your home in a location that is easy for you to go to regularly to observe
• A metal hanger or twine of any kind to attach the metal can to the post (or duct tape could work)
• Soil collected from the ground in the area of the post or stake you are using (enough to fill 1/3 of the can)
• A raw chicken piece (a drumstick or wing you can buy at the grocery store) you will place on the soil in the can
• A screen or wire mesh (or aluminum foil with many tiny holes poked into it to resemble mesh) that can be placed across the top of the can that will cover the opening of the metal can to keep animals out but allow insects in. This should be shaped into a funnel with a 5cm by 5cm hole at the center and deepest part of the funnel that leads into the can. This encourages beetles to fall in but not be able to get out. You will need to secure this mesh or aluminum around the outer edges of the can with tape or twine so that it does not blow away.

What To Do: 

  1. Watch the video at the top that shows RMBL beetle scientists in action. Pay close attention to their coffee can and mesh traps!
  2. Construct your beetle trap using the materials listed above. It is OK if it is not perfect!  Your observations are not being used for actual research in this challenge; this is for you to get to learn more about beetles.  The main intent for the trap is that it needs to be off the ground (to make it more difficult for scavengers and other animals to grab the bait) and that the mesh or foil on the top of the can is shaped to funnel the beetles into the hole in the middle so that they drop down to the chicken leg bait.
  3. Visit your trap daily to see if you have captured any beetles, or if something has happened to the bait and it needs to be replaced.
  4. Record observations of your choice in your field notebook about how the chicken leg is decomposing over time as well as each day that you see burying beetles.
  5. For each day that you see burying beetles, draw or take a picture of each beetle, and record the differences in their appearances. You may have males and females, and you may see different species.  There are over 180 known species of burying beetles.  To identify the beetles, here is a Key to the Carrion Beetles of Colorado and Photographic Key to Burying Beetles (Rocky Mtn. West).
  6. After recording your observations, gently release the beetles back into the wild.

Please Remember (Research Rules & Ethics): Keep yourself healthy and safe by either using gloves when handling the raw chicken and beetles, or being sure to wash your hands with soap and water thoroughly after handling these organisms.  Handling raw chicken can cause you to become very sick through salmonella poisoning, so safety precautions are essential.  If you handle the beetles, be very gentle so that you do not damage any body parts.  Avoid their mouth as well because they can bite (it feels like a pinch). Trapping and handling is an invasive way to study organisms.  It is important to take this responsibility seriously and check your traps daily so that the beetles do not die in the trap.

What Happened? Tell Us About It!  If you find beetles in your trap, email your observations to explain what you found!  We want to know the habitat type where you placed the trap, when you saw beetles, and how many different types you saw (based on their differing appearances).

So What?  Next Steps: Learn more about burying beetles and the variety of research taking place at RMBL by watching the recording of the lab chat.  There are also more RMBL beetle research resources and experiment instructions here: