Raising monarchs inside
Raising monarchs in aquariums
Why do this? For one thing, of course, it's fascinating!
For another, though, it's a way to maxmize the number of eggs that actually turn into butterflies.
I've read estimates that only 5-10% of the eggs laid survive to butterflyhood.
Parasitism, predation, weather, even milkweed latex all take their toll.
Of course, low survival rates are common with insects—we'd be overrun with insects if every insect egg laid actually survived to adulthood.
First, I want to stress that I'm NOT breeding them (i.e. collecting eggs from a captive mating pair) NOR am I buying eggs. I'm collecting only those eggs that are laid naturally in my own yard.
After a few years, I started keeping only the part of the leaf the egg was on, instead of cutting the whole stem for each egg. Note that the bits of leaf are on a moist paper towel.
I did this because I was afraid I'd run out of milkweed, and using a whole stem for just one little egg wastes the milkweed. It would no longer be fresh by the time the little caterpillar was big enough to need it.
Of course, using this method, I had to monitor the eggs frequently so I could transfer any new little caterpillars to an aquarium with more milkweed. I was surprised at first to see that as soon as they hatch, they're apt to go "exploring." I think I lost some this way. Since I work from home, I'm able to monitor them frequently.
Their first milkweed (outside the aquarium just for the photo)
Starting in 2011, I started keeping the eggs I collect at any one time in one container, but no more than ten in one container. With the decline in population, every egg is precious, and I want to minimize the chances of spreading disease or parasites.
(Unfortunately, in 2013 I didn't find any eggs to raise, and in 2014, I had a maximum of three at one time.)
Since I became a habitat gardener, I rarely bring flowers into the house as I used to do. Now I'd much rather be enjoying my beautiful flowers outside where I can see all the creatures enjoying them, too.
So this is a good use for all those vases I had accumulated. And they're easy to sanitize by running them through the dishwasher.
I put the vases in a 10-gallon aquarium that we've sterilized with a 20% bleach solution.
Their first day out of the egg
In their first day out of the egg, they've already eaten some holes in the leaves of this tender young milkweed.
It was fairly cool for August when I collected these eggs. It was interesting to see that it took a few days longer for them to emerge due to the cool weather. The whole process goes much faster when it's warm than when it's cool.
(Yet one more example of why we must be concerned about climate change.)
A few days later, now 1 mm long
At this young stage, they're pretty easy to take care of. Even though they're eating all the time, they're so small they don't make much of a dent in the leaves. They've grown a lot, but they're still just 1 mm long.
That will soon change!
I've had quite a few swamp milkweeds growing around my compost pile, so I have a ready supply of these young milkweed plants with very tender leaves—sufficient for the vastly reduced numbers of caterpillars I was able to raise in 2014.
Until the monarch population declined in 2013, I had been raising them in five 10-gallon aquariums. After seeing the first few caterpillars pupating underneath the very edge of the aquarium, and also under the little triangle of cardboard on the upper screen, I realized they were looking for cover, so I put some cork hotpads on the top. (This was just something I had handy that would stay in place—there's nothing special about cork…) Since their silk pad sometimes attaches right to the cork, I didn't want anything that would slide around. It worked! They started attaching themselves underneath the pads away from the edge.
We now have an improved method. We tape a manila file folder to the top to provide the cover they're looking for. We just throw them away when each batch is finished, then replace with a new, clean one.
One thing we learned was how valuable it is to have one extra aquarium without a top. Once you have chrysalides attached to the top, where do you put it when you're adding new caterpillars or milkweed, or if you're cleaning the aquarium? It's handy to be able to place the top on an empty aquarium.
These caterpillars are real eating machines. In fact, when there are a lot of large caterpillars in an aquarium, their munching is clearly audible. I love hearing it!
We clean the aquariums frequently—every few days when they're tiny, but every day when there's a lot of bigger caterpillars. They create a lot of frass (caterpillar poop)!
We take this as an opportunity to count the number of caterpillars we have of each instar so we can chart their growth, but especially because we don't want to accidentally lose any in the cleaning process. We make sure we end up with the total number we started with. It's easy to overlook tiny caterpillars.
It's quite a production (and somewhat time-consuming) when you're raising this many, but it remains fascinating—and it's only about ten weeks of the year.
An aquarium where I raise the monarchs
Here's one of my five aquariums filled with monarchs in various stages.
They go through a LOT of milkweed, so we make sure we have a large supply available.
We need more than would be necessary if they were developing outside. First, more of the eggs laid will survive than would survive outdoors, so more total milkweed will be needed. Second, the milkweed doesn't last as it would if it were still part of the plant. Once we cut it to bring inside, it's just like a cut flower.
I like to have fresh milkweed instead of tired old stuff so I change it frequently. One summer, I actually ran out of milkweed and had to drive to a spot I found where some was growing in a ditch. Now I plan to grow a lot more milkweed year since I didn't like having to make those early morning trips!
The first year, we were somewhat alarmed when we saw drips of what looked like blood on the bottom of the aquarium right after they emerged ("eclosed"). Then we learned that this was meconium, the same type of metabolic waste human babies expel after birth. They continue to "drip" for a while, but the fluid becomes clear. This shows the drippings from a few monarchs in one of our aquariums.
On the other hand, the clear greenish or amber liquid called "hemolymph," not blood, is what inflates the wings.
Many prefer pupating on the top screen
But virtually all the problems monarchs are encountering are new and human-caused: loss of habitat in general, loss of milkweed specifically, climate change, as well as illegal logging and general turmoil in Mexico's overwintering areas.
Although I may have saved some individual monarchs by raising them from eggs, the ultimate solution is not raising them, but creating habitat in the wild: i.e. planting milkweeds!
They don't all survive
They don't all survive. Perhaps these two had a parasite.
All in all, though, we've had only a miniscule number that haven't become beautiful, healthy butterflies.
Here's a stinkbug nymph dragging away a caterpillar it has killed. I was wondering why my daily caterpillar count was decreasing! Now I'm checking the leaves before I bring them in.
This shows the scale of the stinkbug, and thus the caterpillar it attacked. There's a lot of drama in this small world.