Saturday 29 September 2018

The adventures of Eagle the caterpillar

Two years ago, we were given an Eastern Black Swallowtail egg to raise. This was the start of a fascinating summer hobby for myself and my daughters. Last year we raised and released 3 Monarch butterflies. This year we released 39 Monarchs.

That's not the story I'm telling today though. Today's tale is the story of an Eastern Tiger Swallowtail named Eagle.

While I was outside one day, I saw an Eastern Tiger Swallowtail. I don't normally see many swallowtails around here, so I watched it for a few minutes. It flew up to a tree on the edge of our yard and fluttered by a couple leaves before flying off.
I knew the butterfly wasn't eating as there were no flowers, so I looked at the leaf where it was fluttering and found this:



Huh. That could be an egg. Hello Google my friend. It turns out that eastern tiger swallowtail eggs look just like this and are often found on wild black cherry trees, which Google again helps me ID this tree as. The butterfly hung out by another leaf, but it was too high for me to reach from the ground. By the time I got back with a ladder, I couldn't figure out which leaf it was.

This butterfly in potentia had quite an adventure even before they hatched.
I picked up the leaf at one point to put fresh, wet paper towel around it and the egg fell off of the leaf. I didn't know that was possible. Thankfully it landed on the table and not on the floor. The next day, Thing 2 picked up the leaf that I had set it back on, forgetting that I had said not to touch it because the egg was no longer attached to he leaf, and the egg fell off again. I wasn't in the room to see exactly where she was when this happened. We looked and looked and couldn't find the egg. By this time the egg was starting to turn tan, which was normal, so it blended in quite well with our off white carpet.

The next day, I made one more attempt to find the tiny egg and was able to find it. Whew! I reissued the directions that no one was supposed to touch the container that had that egg in it and hoped for the best.

A couple days later, the egg had changed again and I suspected it was getting close to hatching.



I was right. Later that day, we had an itty bitty caterpillar. Now I was super glad that I found that egg, otherwise this poor caterpillar would have been searching for food on our floor.  Monarch caterpillars will eat their egg shell first thing, but this caterpillar left it uneaten.


The caterpillar usually hung out in the center of the leaf, so I got a bit concerned that they weren't eating, but then little bits of the leaf were disappearing.

About 3 days post hatch (PH) more of the leaf was gone. The egg makes it more apparent that they are growing than without something for reference.  In this next picture, you can see the marking well that earned Eagle their name. My daughters thought it looked like an eagle on their back.

It's shedding time! Unfortunately, this was the only time I noticed that they had shed, even though they must have shed more than once. You can see the shed skin behind Eagle and the bit that covers the head to the left. This is five days PH.
They do move! Eagle usually hung out in the middle of the leaf on a little silk pad they made so we rarely saw them eating. This picture is through the plastic of the enclosure I had them in because I wanted proof that they ate without disturbing them. This is still 5 days PH.

There are many photos with my thumb for size reference. Eagle is getting white legs! I guess you can see them in the above picture as well, but th is was the point that I started trying to get top and side pictures. This is 9 days PH.

Much more white on 10 days PH, but the eagle is still obvious. We also see the first hints of green starting above the head.
Here you can really see how their head is below the "head" with false eyes. The true head is the dark area on the right. When the caterpillar is resting, their head is often tucked under the front of their body so that predators think that they're bigger with that fake head and eyes. The false eyes will be on the thickest part of the body just before the abdominal prolegs they're standing on. The thoracic legs are held close to the body right behind their head in this picture. They're also more green here on day 12 PH.

Eagle is much more green on day 13 PH. So far the eagle is still prominent. Further to the last picture, you can't see their head when looking from above.
In this picture you can also see the silk pad that they hang out on. Hey, if I could lounge around on silk all day, I'd go for it!
Here's a picture from day 14 PH. You can see their head tucked under their body. Their fake eyes are becoming more prominent and the eagle is fading.
I'm a vicious snake! Predators beware! Day 16 PH.
All stretched out on day 17 PH. You can see their thoracic legs. The eagle is almost gone :(
The leaf Eagle made their pad on is starting to close up. For now, they're still hanging out on that leaf. They're getting a yellow stripe across their "neck". 18 days PH
They look angry. I wouldn't mess with them. 18 days PH
How weird. They're not on their leaf. I don't know when they usually ate during the day, but whole leaves were starting to disappear in these later days.


Not too much changed in the last week or so. Wrinkly face at 23 days PH
26 days PH.
I'm watching you...
Or not. Eagle's face is tucked below as usual. Day 30 PH. This is another good look at the silk pad they rest on. The leaf they've been on all this time is really starting to curl up.

More Day 30 PH. Thumb for scale.
Day 33 PH. Wow. Is that Eagle? 
Yes, yes it is. They suddenly turned brown. I had read that this was a sign of imminent chrysalis preparation.

The pattern in the brown is really quite beautiful.

I would have liked to get better pictures of them as they were preparing their chrysalis, but I didn't want to disturb them too much. I was thrilled that they were making their chrysalis on a stick rather than on the enclosure. That would make keeping them for the winter easier to figure out. They are right near the bottom of the stick.  34 days PH

A closer view of Eagle. Here you can see the belt they make for themselves. It's attached to the stick, then they lay back into it so that they're only touching the stick at their back end. Again, no picture of this because I could foresee bad things happening if I tried. Eagle had made it this far. I didn't want to risk any problems that would be due to my meddling. In the picture their back end is hiding under the sticks to the right. The vertical white line is their belt, with their head just to the left of it.

At 35 days PH, Eagle looks quite different. As Thing 1 pointed out, they look like a branch and that helps keep them safe. They still have that belt around them. For these pictures, I pulled the stick out and am holding it more vertically than it was in the enclosure. Considering that the belt is the only thing holding them on, they seem pretty secure. I imagine the little patch near the top end to be a sleeping mask while they rest through the winter. 


Rest well, Eagle. I'd like to say "stay warm", but that's unlikely here in Michigan. I've read that they make a form of antifreeze so that they can make it through the winter. This is the normal way that these butterflies overwinter, so I try not to feel bad about leaving them out there.

My next post will pertain to the winter enclosure that I put Eagle in and the location that will hopefully keep them safe.

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