The Black Death

I was planning my next post to describe how I raise the caterpillars inside my house. Unfortunately my charges have been hit by some noxious element. I have to keep in mind that already this summer I have seen 12 new monarchs fly from my "nursery". It is a setback but I am trying to ascertain what happened.

This photo shows the simplest case of caterpillar death. They look like a railroad car that has fallen off the track. They just flop over. I have seen black ones and failed chrysalises.


I searched the internet and found this useful site. There are a lot of different dangers that confront monarch raisers. One way to get an initial grip on remedial steps to take is to see what suggestions appear under each ailment. There are two to keep in mind: air circulation and... I forgot the other one. Oh, I guess it was cleanliness. Actually they both go together.

The linked site mentioned the source of milkweed plants. I recently bought 4 more from a trusted nursery. I need to check with them to see if they used pesticides in their plant production process.

In my case I am concerned about chemicals in the plastic boxes I just bought. Perhaps they need to be aired out well before use. I borrowed an old trick from my aerospace days: I outgassed them.

Early in the space program in the early 1960's, one of the astronauts reported some gunk on his window. It turns out that if parts have some volatile compounds on them when launched into space, the high vacuum of space causes the gasses from these compounds to come out or outgas. Then they can deposit themselves on nearby surfaces like windows and camera lenses. In the building I worked in at Marshall Space Flight Center, Huntsville, Alabama, they had a house-sized vacuum chamber. Any incoming parts for spacecraft built there at Marshall were first put into this chamber under a hard vacuum for several hours in expectation of ridding the parts of volatile compounds.

In the case of my plastic shoe boxes, I put them in the oven at 160 degrees F for a couple hours.

A Monarch Butterfly Garden

There are two types of plants to consider: Nectaring plants and host plants.

Nectaring Plants

Invite the monarchs to lunch. Monarch butterflies sip nectar from many popular flowers. You may have some favorites in your garden already. Start by checking listings of plants for your part of the country. This site has a selection of plant lists for different parts of the country. I live in the Detroit Metropolitan area and have several of the plants from the Great Lakes list.

I have noticed that monarchs and other butterflies really like the coneflowers (Echinacea). Also in my garden are Black-eyed Susan (Rudbeckia), Joe Pye Weed (Eutrochium), and Swamp Milkweed (Asclepias) which is also the main monarch host plant.

Monarch Watch has plant information as well as everything else you will ever want to know about monarchs.

Host Plants

The only plants that monarchs lay eggs on are in the milkweed family. Swamp milkweed (Asclepias incarnata) is the preferred plant for anyone who wants to raise monarchs. It is a very attractive plant and has an attractive flower head. I have a link to photos and other information in the first post to this blog.

Common milkweed is another possible host plant for your garden but it is no beauty. Also it tends to spread unlike the swamp milkweed which stays where you plant it.

The final member of the family that I have seen listed as a host plant is the butterfly [milk]weed (Asclepias tuberosa) but I have never seen any sign of eggs or caterpillars on my butterfly weed and I have been reluctant to offer it to my protected caterpillars.

Once you have some established swamp milkweed you can save the seeds in the fall and start your own plants in the spring. The seeds need to be exposed to cold conditions for successful germination. You can just put them in your freezer for a month to accomplish that hardening.

Raising Monarch Butterflies

Some years ago I learned about rain gardens. The logic is that instead of directing rainwater into sewer systems, why not put it to work growing things and give the infrastructure a break. One of the plants that does well in wet conditions is the swamp milkweed, Asclepias incarnata. For a plant with a questionable sounding name, it is very pretty. See here. It is not at all like common milkweed.

Both common milkweed and swamp milkweed are host plants for Monarch butterflies. That is they lay their eggs on it and the resultant caterpillars eat it and grow up to be big, strong caterpillars.

The female Monarch lays a single egg on the underside of a leaf. They are very small white globes.

Monarch populations rise and fall but this seems to be an especially good year. I cut off this stem because it got broken off by my clumsiness and there was an egg.

Only about 2 out of every hundred eggs develop into an adult Monarch butterfly. They are preyed upon by ants, spiders, and birds. So I bring them inside and raise them in a plastic shoe box. It is best if you find just-hatched caterpillars because I am not sure how long the leaves remain viable before they dry out too much.

When they are very small caterpillars it takes them quite a while to get going but once they get to be, say, 3/4 inch long you have to check on them a couple times a day to see if more leaves are needed. The amount of leaves in the above photo is actually more than is typical.

If you find several eggs near the end of a stem, cut a few inches of it and put it in a vase inside.

By the way, I will expand on certain points of caterpillar husbandry in later posts but, for now, I just what to present the basics.

So to raise these guys you just add leaves each day as needed. Keep the box covered (it is nice to use a box with a clear lid) because when they are ready to pupate they will climb to the top and do it there. As they grow they produce a lot of poop (called fras). You will need to clean this out but I will cover that in a later post.

Again, I'm just providing the basics here... After they pupate it will take 10 to 14 days to develop. When they are within a day of emerging the pupa will begin to look transparent (darker). Make sure you take the box lid outside and support it with a clamp or something that leaves the underside clear for them to fly away. My videos, below, will give an example of this.