Why Raise Caterpillars?

Raising caterpillars at home is one of the most accessible and educational wildlife experiences available. It requires minimal equipment, costs very little, and rewards you with a front-row seat to one of nature's most dramatic transformations — metamorphosis. Whether you're a teacher, a parent, or simply a curious adult, this guide will walk you through everything you need to get started.

Step 1: Find Your Caterpillar

You have two main options for obtaining caterpillars:

  • Find them in the wild: Look on plants, especially the underside of leaves. Always note which plant you found the caterpillar on — this is your first clue about its diet.
  • Purchase from a reputable supplier: Many educational suppliers sell butterfly kits with caterpillars and food included. These are a reliable option for beginners.

Important: Check local regulations before collecting caterpillars. Some species are protected, and rules vary by region. Only collect common species and take no more than you can care for well.

Step 2: Set Up the Enclosure

Caterpillars don't need elaborate housing, but their enclosure should meet a few basic requirements:

  • Ventilation: A mesh or screen lid is essential. Poor airflow causes mold and respiratory problems. Never use a fully sealed container.
  • Size: A simple mesh pop-up cage (available cheaply online) or a large jar with a mesh lid works well. Larger is better for bigger caterpillars.
  • Surfaces for pupation: Include a sturdy stick or two for caterpillars that hang their chrysalis, and some crumpled paper or loose moss for species that pupate on the ground.
  • Substrate: A layer of paper towels on the bottom makes cleaning easier.

Step 3: Feeding Your Caterpillars

Getting the diet right is the single most important aspect of caterpillar care.

  • Identify the species first: Different caterpillars eat very different things. Monarch caterpillars need milkweed; swallowtails need parsley, dill, or fennel; luna moth caterpillars need tree leaves like walnut or birch.
  • Use fresh leaves: Place cut stems in a small vial of water to keep leaves fresh. Seal around the stem with cotton wool or floral foam so caterpillars cannot drown.
  • Avoid pesticides: This cannot be overstated. Even trace amounts of systemic pesticides can kill caterpillars. Grow your own host plants organically, or source from a trusted pesticide-free grower.
  • Replace food daily or when wilted.

Step 4: Daily Maintenance

Caterpillars produce a surprising amount of frass (droppings). Daily cleaning keeps the enclosure hygienic and reduces the risk of bacterial or fungal infection:

  1. Gently move caterpillars onto a fresh leaf before cleaning.
  2. Remove old frass and any wilted or uneaten leaves.
  3. Wipe down the interior of the enclosure if moisture is building up.
  4. Replace the paper towel substrate.
  5. Return fresh food and replace caterpillars.

Step 5: Watching the Life Cycle

As your caterpillar grows, you'll observe it molt (shed its skin) between each instar stage. Signs that a molt is coming include:

  • The caterpillar becomes still and stops eating for 12–24 hours.
  • It may look slightly shrunken or dull-colored.
  • Do not disturb it during a molt — interruption can be fatal.

When your caterpillar is fully grown, it will search restlessly for a pupation site. This is normal behavior — called the "wandering stage." Ensure it has appropriate surfaces to form its chrysalis or cocoon.

Common Problems & Solutions

Problem Likely Cause Solution
Caterpillar not eating Wrong food plant, about to molt, or unwell Offer different leaves; leave undisturbed if molting
Mold in enclosure Too much moisture, poor ventilation Improve airflow; clean more frequently
Caterpillar is dark/shriveled Viral or bacterial infection, dehydration Isolate from others; ensure fresh food is available
Chrysalis fell Not secured properly Gently re-hang with dental floss using the cremaster (tip)

Releasing Your Butterfly or Moth

Once your adult butterfly or moth has emerged and its wings have fully dried and hardened (allow at least 2–3 hours), release it near appropriate habitat. Choose a warm, calm day and release in an area with nectar plants and host plants for the species. It's a genuinely moving moment that makes all the care worthwhile.