Monday 1 October 2018

Chrysalis' winter home

In my last post, I chronicled the egg and caterpillar stages of Eagle, our Eastern Tiger Swallowtail. At the end I had a chrysalis from which a butterfly wouldn't emerge until spring.
What to do with them?!
I knew we couldn't keep them inside. The warmth and artificially lengthened days (hey we use lights in our house...you know, to see) would likely mean that they would emerge too early to be able to find food in the wild. I took on responsibility for this life when I brought their egg into the house, so I had to figure out a way to put them outside and be protected. I've seen posts where they put chrysalises in an unheated 3 season room, but I don't have that option.

I had three important considerations.
1. Keep out predators like mice. This was the biggest concern as I know we have mice around here. I've seen them in our garage, so I didn't want to just set the container in the garage.
2, Keep out artificial light at night since that would make them think the days are longer than they really are. We have a light with a photosensor that turns on when it gets dark outside, so I'd have to be careful where I put it.
3. Correct humidity. They need to not dry out, but I've read that outdoor humidity is fine, but inside the house can be too dry since heating the air tends to dry it. This basically meant that the container needed to be open to the air. I did have to think about keeping out rain and snow, especially since the chrysalis was so close to the bottom of the stick. I didn't want to drown them.

This is what I came up with.

My parents gave me this coffee can with a handle for berry picking. it's metal, so it's unlikely that mice will chew through it.  It held 3 pounds of coffee, so it's a decent size.

I didn't want to have the chrysalis right next to cold metal, so I cut out a circle of  cardboard for the bottom and a rectangle of cardboard to line the side. I just used corrugated cardboard from a box that we had received a delivery in.

I thought this would work well enough, but I had to come up with some sort of lid. I wanted it to be rather open to the air, but needed to keep out mice.
I had some hardware cloth left over from a previous project, so I thought I could use that to keep out the mice.
First, I cut out a couple squares of hardware cloth and bent the corners over the edge. This showed me where I would need to tie the lid down. I drilled some holes in the can in pairs and fed twist ties through the holes. The label came loose when I did the drilling, so I pulled it off. It's still the same can.

The twist ties should hold down the lid well enough to keep the mice out. I'm hoping that the little bit of metal in the twist tie (and the location) will prevent them from chewing through it.
Mice can squeeze through holes that seem too small for them, so I turned one layer of the hardware cloth 45 degrees to make smaller holes.
It was time to add Eagle and get them outside. The stick was a bit too long for this container, so I broke a bit off of the top.
Eagle was right at the bottom of this stick, but they're laying at a similar angle to when they made their chrysalis. Blogs I've read seem to indicate that this angle doesn't matter. I could have removed them from the stick, laid them on the bottom of the container and just made sure to have something for them to climb up when they emerge and they'd have been fine. I was still happy that they made their chrysalis on the stick.
Rest well, Eagle. See you in the spring!


Location, location, location.
As I said, we have a light that stays on all night on the front of our garage. We also have this entryway that seems like it would be great shelter from the wind and precipitation. With the opaque container that was only open on the top and the entryway having an opaque section at the top, I think we found a great location.

It gets quite dark in that corner and there was even already a hook there! They should be out of the worst of the wind and I shouldn't have to worry about them ending up in a puddle since they shouldn't get any snow or rain in there. We just need to remember to check on Eagle regularly in the spring. I don't know when to expect them to emerge, but I've read that it's triggered by warmer, longer days.
The location has the added bonus that we walk by here every day, so hopefully we'll check on them regularly.

It's weird to know that we'll have that chrysalis out there all winter, but I keep reminding myself that these butterflies normally overwinter as chrysalises. I'm still nervous about having done something wrong that would lead to them not emerging, but time will tell.



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