Wednesday, November 23, 2016

Caterpillars 2016-- I Might Have Gone A Bit Crazy

This year was a weird one for raising Black Swallowtail caterpillars. It's been six years now that I've done this (see here, here, and here), and in some ways I still feel like I'm just getting the hang of it. However, I think this fall was the most successful I've had in terms of how many chrysalises will be my companions for the next few months as they overwinter. Some people might even say I went a wee bit caterpillar crazy! :-)

The first two caterpillars of 2016 (that I found...)

The caterpillar season started slow this spring, due probably to the late cold weather we had. Finally in early May I found two big third-instar caterpillars chomping away on my garden dill. Hooray! A couple weeks later I found two more caterpillars, younger than the first two. That was it until the end of the month, when I found six tiny cream-colored eggs on the feathery dill plants. I was keeping a really close eye on the dill patches, it surprised me that it took so long and that I found so few eggs or caterpillars to start the summer. The single chrysalis that I had overwintered from 2015 took a long time to eclose too. The butterfly didn't come out until a couple weeks after I found those first two caterpillars! It was pretty nerve-wracking for a while, I was afraid it had died sometime during the winter.

So I had ten caterpillars total to start out. They all successfully pupated and I released them in the front yard near my flower garden. I have lots of dill growing freely in the garden, along with plenty of carrots. Despite plenty of larval hosts, however, I then entered a two-month dry spell of not a single egg or caterpillar found in my yard. I also plant lots of colorful flowers to attract and feed the adult butterflies, but saw no more Black Swallowtails of any phase in my yard until early September.

All three phases at once: freshly eclosed female, chrysalis under the far twig, and a teency caterpillar in the dill.

The second generation hatched and matured somewhere nearby, though, because on Labor Day weekend I finally found 15 (!) eggs-- long after my adults from earlier in the summer would have died. The majority of the eggs were on dill, and a few were on carrot greens. Fourteen of the eggs hatched about a week later. The fifteenth turned dark as if it was going to hatch like the others, but it never did.  A few days after Hatch Day I also found five more tiny caterpillars in the dill, surely from the same batch of eggs. We are very careful during the summer to meticulously examine all dill or carrot greens we pick during the summer, to make sure any eggs or caterpillars are given a chance to survive. On any given evening you're likely to find me and V in the kitchen turning a fragrant handful of feathery fronds over and over, looking from all angles for little cream-colored eggs or tiny black-and-white caterpillars clinging to the leaves. I definitely don't want to chomp into a little caterpillar when I'm eating my salad, or inadvertently slice one while chopping the herbs for a sauce! I also try to check the plants still in the garden at least every few days, usually on my way to the car in the morning or when I come home in the evening.

The same photograph as above, cropped to show the teency caterpillar better.

Over the course of September I found eight more caterpillars out in the garden, and brought them each in for protection from predators and parasites. My home office was full of busily munching larvae, and as they grew bigger and bigger I was kept hopping trying to make sure they never ran out of fresh dill or carrot greens to eat. I spent a lot of time trying to keep their cage clean, as well. Caterpillars are such little poop machines! I guess all baby creatures are, come to think of it. Unfortunately, I was so busy I forgot to take any photographs of the craziness.

Lots of dill in my garden-- it just about takes over! Good thing, I needed a lot with 27 caterpillars at once.

Once the caterpillars were getting huge and fat in their last instar, I put lots of branchy sticks in the cage, in hopes of convincing all 27 to pupate on convenient spots rather than attaching to the sides of the cage. Despite my efforts, though, when they were ready to pupate, some of the caterpillars chose to be extra contrary and crawled DOWN into the bottom of the glass bowls I use to cluster  individual water vials for the greens (see the purple one in the photograph above). I had never had any try to hide in the bowls before, and only noticed them one morning when I was putting fresh water in the vials. This meant that they'd been lying in shallow layers of their own and their siblings' poop for a day or two, yuck! (From now on I'll be checking those bowls more often!) I hastily pulled them all out and laid them on clean paper towels in the bottom of the cage. They were already in the prepupal phase, just waiting to dry out enough that they could molt into their chrysalis. I didn't know if they would be able to successfully molt while lying on the ground like that, but didn't see that I could do anything else since I'm unable to spin silk like they do.

Over the next few days I gently turned these prepupae over daily, making sure both sides got exposed to the air. As I did this, more and more of the other caterpillars started getting restless and wandering around the cage in search of a spot to pupate. In the end, all the other caterpillars did choose one of my twigs for pupating. I think this is the first year I don't have any chrysalises stuck to the sides of the cage!

Finally, one day I came down for my coffee in the morning and checked on the cage like usual. It was a joy to see that one of my "fallen" prepupa had successfully molted into a perfect brown chrysalis there on the floor of the cage. Hooray! Over the next three days all the other fallen prepupa did as well.

They are still lying on the floor of the cage as I write this. (I am away from home this week, and don't have a photo with me. I'll update once I get home, though.)Now that they're successfully in their papery chrysalis, I plan to attach them myself to twigs. I don't want to run the risk of them eclosing there on the ground and their wings drying crumpled, as I think might happen if I didn't fix things. I have reattached chrysalises before, and it's relatively easy. There's usually one or two who don't create secure enough attachments to their twig and either fall to the ground or otherwise need relocation, so I had to learn how to do that. I'll write a future post about reattaching a chrysalis, stay tuned. 

All in all, despite those empty months I had a pretty good summer for raising caterpillars. I even tried my hand at another species-- a Variegated Fritillary. Their larval host is the common violet, so I've let a LOT of violets colonize my garden areas. I found one late-instar caterpillar a couple years ago, but at the time decided trying to raise two species at once would be too complicated.  This summer when I actually saw a Variegated Fritillary oviposit in my yard, I brought one egg inside to raise. Sadly, the caterpillar failed in its second instar. I don't know what went wrong, but I'm glad I got the chance to try anyway.

One of this year's Black Swallowtails, just before she flew off into the wild.

My totals for this summer are as follows:

Eggs found: 21 Black Swallowtail, 1 Variegated Fritillary
Eggs hatched in captivity: 20 Black Swallowtail, 1 Variegated Fritillary
Caterpillars found in the wild: 17 Black Swallowtail
Caterpillars molted to chrysalis: 37 Black Swallowtail
Overwintered chrysalises successfully eclosed: 1 Black Swallowtail
Summer Chrysalises successfully eclosed: 10 Black Swallowtail
Failures: 1 Black Swallowtail egg, 1 Variegated Fritillary caterpillar
Chrysalises to overwinter into 2017: 27 Black Swallowtail

Stay tuned til the spring to see how my overwintering chrysalises do!

I'm linking up with Saturday's Critters too.


  1. Hello, what a great post. A lesson for others that may want to try raising butterflies. Thanks for sharing the info and the photos are great too. Thank you for linking up and sharing your post. Happy Monday, enjoy your new week!

  2. BTW, here is a link that shows when the dates of Lakeland Swan roundup.

  3. Excellent, thanks Eileen! I'm planning a post in February about how to get started raising butterflies for fun. I just started drafting it this morning! :-)


Blogger Widget