University of Minnesota

Making a Rearing Cage

Larvae Containers

Plastic rearing tub (Photo: Monarch Lab)

There are many kinds of containers that are suitable for larvae. The only requirements are that the container has good airflow and is big enough for the caterpillar(s) and host plant leaves or clippings. A washable container is also preferable as well as one that allows for easy observation. Good rearing containers include:

  • Mason jar covered with panty hose
  • Plastic deli container (1 quart) with 1" holes cut in the lid and covered with netting
  • Shoebox with screening/netting attached to lid (sometimes available at our online store)
  • Ice cream pail covered with netting
  • Aquarium with screen top

For a more permanent container, you can cut windows in plastic containers like ice cream pails and attach screening with a glue gun or duct tape.

The larva container needs to be at least four inches deep so that the emerging adult has room to hang from its chrysalis casing and allow its wings to expand and harden. Once this has happened, you should move the butterfly to a larger cage or release it. Alternatively, you can move the pupa to an adult cage or simply hang the pupa in a safe place until the adult emerges. Adults should not be left in small larva containers.

Butterfly Cages

Wooden Frame

This cage works well for rearing larvae and holding adult butterflies. If your larvae pupate in this cage, they will be easy to observe as they emerge as adults and will not have to be handled until they are released. The dimensions of this cage were chosen to make efficient use of the plywood and screening that we buy. They can be modified!

  • Two 12" X 16" X ½" plywood boards
  • Four 1" X 1" X 22" wood posts
  • Four 14½" square edge molding pieces (trim)
  • Three 12" square edge molding pieces
  • Eight 1" corner braces
  • One 2' X 4' piece fiberglass screening
  • One 2' X 1' piece fiberglass screening
  • 6' X ½" Velcro
  • Sixteen 1/2" wood screws
  • Eight 1-1/2" sheetrock screws
  • 5/16" heavy duty staples
  • 9/16" heavy duty staples
Assembly Instructions
  1. Double stitch fuzzy side of Velcro on three sides of 2' X 1' piece of the screening, leaving a 1' side without Velcro.
  2. Screw posts onto corners of one of the plywood boards. Screw other board onto the top of the posts. Pre-drill all holes for screws.
  3. Screw brackets into corners, attaching 2 brackets per post. It's easiest to use a power drill with screw attachment.
  4. Wrap large piece of screen around three sides of cage (all but the front), attaching screen with 5/16" staples to the posts. There will be overlap of screening at the top, bottom, and front edges of the cage. This will be tucked under the molding, or stapled under Velcro.
  5. Staple three strips of Velcro to the front of the cage, on the outside edge of the two front posts, overlapping the screening, and on the bottom plywood edge.
  6. Attach the front screening panel using the Velcro.
  7. Finish the cage by attaching molding. Staple (with 9/16" staples) or screw the square edge molding to the top and bottom edges, covering all edges except the bottom front edge where Velcro is attached.
Hanging Cage (Photo: Monarch Lab)

Hanging Butterfly Cage

This cage has the advantage of being able to collapse into a manageable size for storage while you don't have butterflies in your classroom. You can make it any dimensions. Many teachers modify this design to make a sturdy, long-lasting cage by using a plywood round instead of cardboard, and building a support structure to hold the cage.

  • Hanger or large embroidery hoop
  • Cardboard round (e.g. from pizza) for base of cage
  • String or rope
  • Toothpicks
  • Paperclips
  • "Bridal veil" netting
Assembly Instructions
  1. If using a hanger, bend into a circle.
  2. Cut a rectangle of netting large enough to go around the cardboard and the hanger, with several inches of overlap.
  3. Close the netting around the cardboard and tie off the bottom.
  4. Attach the hanger or hoop to the netting with paperclips.
  5. Tie off the top of the cage with rope.
  6. Finish by using toothpicks to connect the overlapping flaps.
  7. Hang from ceiling or other sturdy support.

Note: Kid tents (with screening) may be used for large, in-class butterfly cages.

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