Monarch larvae can be reared in many different types of containers. They can be started (but not finished) in plastic petri dishes, or reared in aquaria, glass jars, etc. The trick is usually keeping the food fresh, the container clean and the humidity and crowding low.
An easy method, which requires less daily care, is to place the larvae on entire milkweed plants in pots or whose cut stems are placed in water. These plants are then either placed in screened cages or covered with mesh paint strainers and tied around the base. There are many ways to make simple cages. One method uses wire tomato supports. These are cheap, usually less than $1.00. The frame is used upside down and the tines, which normally are pushed into the ground, are cut off or bent down. To cover these frames make a "sleeve" from see-through dacron or nylon curtain material. The sleeve material is 44"x44". A loop to hold down strings is sewn at each end and the sleeve is then sewn into a tube. The sleeves can be placed over the frame containing the plant and the draw strings tied tightly at each end. Alternatively, the wire frame can be placed so that the bottom rests inside a pizza box filled with clean dry sand. The sand acts as a litter box and the larvae can't crawl under the frame edge if its pushed into the sand.
A similar method can be used to rear Monarchs outdoors on living plants. A sleeve with drawstrings at either end can be placed over a plant, the larvae placed inside, and the drawstrings tied tightly. This method works well and little care is involved. If you don't wish to make sleeves, you could use 5 gallon paint strainers which can be purchased from a local paint or hardware store. The paint strainers with elastic at the open end work best. The larvae are placed in the end of the strainer which is then placed over the milkweed. A baggie tie is used to close the open end of the bag around the stem of the plant.
When the adult butterfly emerges, it must be able to hang and expand its wings. Therefore, pupae must either be hung or placed near a rough vertical surface to climb onto. Picnic food protectors (available from some drug and discount stores for less than $1.50) make good emergence cages (see figure at right). You can use a pizza box as a base, but put a rough surface (screen, old wash cloth, etc.) on the bottom. The pupae can be hung (attach the silk strands at the end of the pupa to tape) inside the food protector or placed on a rough surface at the bottom of the box. The new butterflies will crawl up the walls of the food protector to expand and dry their wings. The attachment cord allows you to suspend cages under lights or in lighted windows. This type of cage is also suitable for mating and egg laying.
Another cage that we use for emergence in the lab is shown in the figure at right. A plastic 2-liter bottle is cut and a strip of fiberglass window screen is placed on the inside for the butterfly to climb up on when it emerges from its chrysalis. This is then placed on a paper towel or other rough surface and the pupa is placed inside as described above.
Wooden Frame Butterfly Cage
- Two 12" X 16" X 1/2" plywood boards
- Four 1" X 1" X 22" wood posts
- Four 14.5" square edge molding pieces
- Three 12" square edge molding pieces
- Eight 1" corner braces
- One 2' X 45" piece fiberglass screening
- 5' X 1/2" Velcro
- Sixteen 1/2" wood screws
- Eight 1-1/2" nails (4d)
- 5/16" heavy duty staples
- 9/16" heavy duty staples
1) Double stitch fuzzy side of Velcro on three sides of 2' X 1' piece of the screening.
2) Nail posts onto corners of one of the plywood boards. Nail other board onto the top of the posts.
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 and bottom of the cage. This will be tucked under the molding.
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 and attach the top edge with staples.
7) Finish the cage by attaching molding. Staple, with 9/16" staples, the square edge molding to the top and bottom edges, covering all edges except the bottom front edge where Velcro is attached.
- hanger or large embroidery hoop
- cardboard round (e.g., from pizza)
- string or rope
- "bridal veil" netting
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 end.
4) Attach the hanger or embroidery 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.
Picnic food protectors (available from some drug and discount stores for less than $1.50) make good emergence cages. Again, use a pizza box as a base, but put a rough surface (screen, old wash cloth, etc.) on the bottom. The pupae can be hung (attach the silk on the inside of the food protector, or the pupae can be placed on the rough surface at the bottom of the box. The new butterflies will crawl up the walls of the food protector to expand their wings.
The attachment cord allows you to suspend cages under lights or in lighted windows. These cages should be suitable for mating and egg laying. Give it a try!
*If, after raising Monarchs with one or more of these methods, you develop an even better scheme, please let us know!