Wednesday, September 28, 2011


Oblong pools of orange, spots of yellow and white surrounded by black edging. The wings of a monarch butterfly are like beautiful stained glass windows. Each butterfly has a slightly unique pattern. Their black bodies are speckled with white dots. Each spring they start their journey from the jungles of Central America flying northward to Canada, a journey of several thousand miles. I’m in the Twin Cities, Minnesota area so it is still a long distance from the mountains of Mexico. Early summer is official when the first monarch butterfly flits by.

My yard is filled with native perennial plants and I purposefully grow a plot of about 50 milkweed plants. They are not particularly attractive but their blooms smell wonderful. I place them inside a fenced area because they tend to tip over mid summer. Monarchs lay eggs on the milkweed plant and the caterpillar larva eats the leaves. Unfortunately, approximately one in one hundred eggs will mature into a butterfly due to weather conditions and predators. I aim to increase those odds by gathering caterpillars and raising them inside. Not all live to maturity but more than ninety percent in my care survive to become a butterfly.

Caterpillars need a space to eat, poop, and a location to attach their pupa chrysalis. They all have bands of white, yellow, and black but there is a lot of variety in the pattern. Last year I had a larva that was mostly black with tiny bands of white and yellow. Their job is to consume calories and grow. In ten days or so they will enlarge by 3000%. They procure all their nutrition from milkweed leaves. However, the frass (poo) is rather gooey and smelly. I will explain the best method to set up a Monarch Caterpillar Hotel. As soon as I see the first caterpillar I prepare the hotel, usually during the first week or so of June in the Twin Cities.

First, obtain a growth tank. I acquired an barely used plastic salamander cage from Goodwill. It is about twelve inches tall, eight inches wide and fourteen inches long. Most importantly, it has a lid with air holes. It is imperative to have good airflow for the caterpillars. Secondly, make a vase for the milkweed plants. I use two disposable plastic containers 2 inches tall and 4 inches square, which perfectly fits the bottom of the cage-hotel. The lid is prepared by poking holes about on fourth of an inch in from the corner and in the center; it looks like a five of dice. Make certain that the hole is about the half the diameter of a pencil so that it will accommodate the stem of the milkweed plant. I extended the hole with cross hatches (like the plastic lid of a soda-pop cup, with an expandable hole to hold straws of various sizes).

Thirdly, prepare the tank. Make certain that it is clean; use a 10% bleach solution (one cup of bleach to 10 cups of water). After it is dry, place a couple paper towels on the floor of the tank. This will sop up any errant fecal matter or chrysalis fluid. Put water into the plastic containers. Place a layer of wax paper over the top of the plastic containers (the wax paper should be a bit larger than the size of the floor of the tank. It will catch the poo as it falls. Make certain that you always close the lid or the caterpillars may crawl out.

The fourth step is food. Pull out some small milkweed plants from the garden. I concentrate on the “volunteer” plants that grow outside the designated milkweed patch. Take the small plant and treat it like a flower, keep the leaves on the stem, just cut the stem to the point that the stalk can be shoved into the hole in the plastic container but not taller than the lid of the container. Usually, mature butterflies lay their eggs on small plants so you might end up with a bonus caterpillar! I use a magnifying glass to look for tiny caterpillars. Don’t attempt to pluck them from the plant, just bring in the whole leaf. Place one plant per caterpillar in the tank. Depending upon the size of the bug and the leaves, they eat about one or two leaves per day. They will chew on the stalk if the leaves are gone. The caterpillars will starve and die very quickly if they do not have adequate food. Don’t touch the larva because they are delicate. I use a dry artist brush to move them if they don’t stay on a leaf.

Maintenance is the fifth step, Replace the stalks every other day or whenever they look droopy. I clean out the whole tank on my back steps because it is too messy to do inside. I temporarily relocate the bugs and the old leaves onto a couple sheets of newspaper while I wipe out the tank, wash the plastic containers, replace the layer of wax paper if it is falling apart, and put in new stalks. Carefully check the old leaves before composting them because sometimes little caterpillars will be on them. Gently transfer the bug to the new leaves. Gently return the caterpillars to the new stalks and they will eat again.

Tillie, the cat, likes to sit on the lid. I have moved the tank to several locations but she still climbs on board. At least she only weighs about eight pounds. I think she is attracted to the smell since caterpillars don’t move much. Sometimes the bugs will climb onto the inside of the lid to molt their smaller skin as they grow. It falls to the floor of the tank. It takes about ten days to two weeks for the caterpillar to reach maturity. When it is at about an inch and a half long, it climbs to the lid and attaches itself. It takes about a day and it will shed its exoskeleton skin to form the chrysalis. It is enthralling to observe a larva dance out of its skin.

Inside the chrysalis, the bug takes about ten days to transform into a butterfly. It is interesting to watch the pod slowly elongate, occasionally wiggle, and then wings can be seen. The pod turns translucent just before it breaks open. The new butterfly emerges with a large abdomen and shrunken wings. It only takes a few minutes and the butterfly forces the fluid from its abdomen to inflate the wings. Fascinating to watch. The wings are very fragile because they are not dry. Don’t mess with the new butterfly until it starts to flap its wings. I take the whole tank outside and gently open the lid. Oftentimes, the butterfly will alight off into the wind. Sometimes, it isn’t quite ready to fly so I coax it onto my finger and I carry it out to the milkweed patch. Gently attach it to any open flowers or a leaf so that it can finish drying its wings. I place them in a sheltered spot so a bird doesn’t swoop down upon the newbie.

Finally, don’t wait to place the butterfly outside. It needs food and flight. It could die very quickly if you leave it inside the tank. I don’t like visiting Butterfly Houses because the bugs are not allowed to reproduce and may not have access to food. They are purely bred for human enjoyment, it is a zoo. Captivity can be cruel. However, I do keep two felines but they would only live a couple years in the wild and they purr a lot.

A second batch of caterpillar eggs are laid approximately the last week of July through the first couple weeks of August. I repeat the procedure above after thoroughly cleaning the hotel with the bleach solution. Otherwise, they will be prone to disease. These hearty creatures will start the migration to the winter grounds in Mexico. Five generations later, a new crop will arrive in my garden to start the process over again. My grandparent’s farm was on the migration route. If your timing was right, you could watch them mass together in the tree branches at night and as soon as the sun warmed their wings, they would fly off in the morning. Alas, after my grandparents died the farm was sold so I can’t watch this wonderful sight.

2011 totals: 31 in summer batch and 19 in fall batch, twice as many as last year since I was super diligent about looking for wee tiny caterpillars. Next year, I’ll note their gender when releasing them. In the fall I collect some milkweed seeds to reseed the area in the spring. is an excellent source of information.

Wish that I could fly.
© 2011

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