Learn about Life Cycle in a Bowl!

What You Need:

  • Plastic container with a lid (a clean whipped topping container works well)
  • Old-fashioned oatmeal, dry and uncooked, about 2 cups
  • Bag of baby carrots, raw (or you can cut several small carrot sticks from a large carrot)
  • 50-100 mealworms (available at pet stores where reptiles and wild bird foods are sold) (Note: When you purchase your mealworms, they will have been refrigerated to slow their growth. To observe their life cycle, though, you will want to keep them at room temperature.)
  • Notebook and pencil

What You Do:

  1. Use a sharp, pointed object to punch small air holes in the lid of the container.
  2. Have your child prepare the habitat for the mealworms: First, put the oatmeal in the container. This is the mealworms’ food. Add a carrot. This will provide water for the mealworms. (There's no need to provide any other sources of water in the container; however, you’ll want to replace the carrot every four or five days to prevent it from getting moldy or drying out.)
  3. Dump the mealworms in the container. It's fine to handle them gently, they do not bite. Be sure to discard of any dead mealworms (dead mealworms appear to be dark brown or black in color). Close the lid and keep the container covered at all times unless you're observing the mealworms.
  4. Now it's time to observe the mealworms like a scientist! Your child should decorate a small notebook so that it serves as an observation journal. 
  5. Have you child draw a picture to show what the mealworms looked like on the first day when they were added to their habitat.
  6. Check on the mealworms once every couple of days or so, and add new entries to the journal. Be sure to have your child date each entry. Some ideas to write about in the journal:
    • How do the mealworms behave when they are handled?
    • Is there any evidence that the mealworms are eating? Growing? Changing?
    • What can your child predict about how the mealworms might change?
    • Encourage your child to ask questions about what he sees. Why, for example, do most of the mealworms tend to hang out near the bottom of the container?
    • Have him design simple experiments to find the answers to his questions.
  7. After about 10 days or so, your child should begin to notice some significant changes in the mealworm habitat. Worm skins show that the mealworms have been shedding their skin, which means that they are growing. And soon, little curved, creamy white creatures appear to be sleeping in the oatmeal. While they may look like mealworm mummies, they're actually chrysalises—mealworm larvae that are undergoing metamorphosis, just as a caterpillar makes a chrysalis before it becomes a butterfly.
  8. Have your child look very closely at these creatures and see if he can see some of the creature's body parts: eyes, legs, etc. Does this creature resemble the mealworms that he put in the container on Day 1? Why not? What's happening? Can he guess what is going to emerge from the chrysalises in a few days? (Note: It's perfectly fine to handle the chrysalises, too. Don't be surprised if they wiggle fiercely in your hand, though. They hate being in the light, and wiggle to try to bury themselves in the oatmeal.)
  9. In a few more days, the mystery will be solved. An adult darkling beetle will emerge from each chrysalis! Ask your child to compare these to the mealworms and the chrysalis shells, and draw a diagram in his journal to show the progression from mealworm to adult. Have him think about his earlier predictions. Was he surprised to see the mealworms turn into beetles?
  10. If you decide to keep the mealworm going a little longer, baby mealworms will soon appear in the oatmeal, and the life cycle will have come full-circle. Adults lay tiny eggs in the oatmeal. The eggs are so small they appear to be fine particles of dust. You may wish to tell your child about the eggs so they understand where the baby mealworms are coming from and include this information in their journal.

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