How to Rear Caterpillars

Rearing caterpillars and watching them turn into butterflies or moths is always interesting and usually very simple. Caterpillars do not have complicated requirements. At this stage of the life cycle, all they basically do is eat and grow. They need a well-ventilated house, the right vegetation and somewhere to pupate.

Things You'll Need

  • Insect guide
  • Fish tank
  • Twigs
  • Old newspapers
  • Disposable cups
  • Paintbrush
  • Cheesecloth
  • Large elastic band
  • Sugar
  • Cotton balls
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Instructions

    • 1

      Identify the caterpillars you wish to rear, if you found them outside. Guidebooks or online guides to the butterflies and moths of your region normally include pictures of each insect's caterpillar. Knowing what kind of caterpillar you have will help you care for them.

    • 2

      Collect several leaves or leafy twigs from the plant the caterpillars were eating. Note what kind of plant it is. Trim the twigs to a little shorter than the height of the tank, if necessary.

    • 3

      Place a layer of newspaper at the bottom of the tank.

    • 4

      Pour about 1 inch of water into one disposable cup. Push the second cup into the first cup.

    • 5

      Push the twigs or the stems of the leaves through the second disposable cup into the water. This arrangement keeps the food fresh but stops caterpillars from falling into the water and drowning. Place the cups and vegetation in the tank.

    • 6

      Place the caterpillars in the tank, on the leaves. To move caterpillars, pluck the leaf they are sitting on and move that. If necessary, use a paintbrush to gently nudge them. Don't handle caterpillars. This may damage them and, if they are toxic, give you a nasty rash.

    • 7

      Secure a piece of cheesecloth over the top of the tank with a large elastic band.

    • 8

      Replace the twigs with fresh ones as soon as the caterpillars eat most of the leaves. If you know what species your caterpillars are, you can the try other plants the guide states they eat. If you don't know what kind of caterpillars you have, or the caterpillars won't eat different plants, stick with the original vegetation.

    • 9

      Replace the newspapers about twice a week or more often if they get dirty quickly.

    • 10

      Observe what the caterpillars are doing each day. When they are large and start roaming around the tank rather than feeding, they are ready to pupate. Replace the newspapers with a layer of soil a few inches deep. Also add the largest twigs that will fit in the tank. Some caterpillars pupate underground, others on plants and bushes.

    • 11

      Release the caterpillars that you found outside once they become butterflies or moths, unless they are pest species. You should keep pest species and any insects bought from a supplier in captivity. Some butterflies and moths do not feed at all, but most can be sustained on cotton balls soaked in a sugar-and-water solution. Use about 1 part sugar to 4 parts water.