Last Friday I went to check on my black swallowtail caterpillars and was a bit worried when I saw only one of the six that were there earlier that morning. I figured that I only have one left so I’ll build a screened enclosure that will still allow airflow but hopefully keep predators out (which is what I thought happened to the rest of the caterpillars). That night I started to get materials together from around the house. I had a few spare 2×4 boards and some leftover screen from a couple of previous projects. I made a bunch of quick cuts and started building. I didn’t finish that night because the mosquitoes were very bad on the patio. I spent the morning (Saturday) fishing with my dad and checked on the remaining caterpillar that afternoon. To my surprise there were two more caterpillars on the dill. Not brand new little ones but the larger ones that I thought had been eaten by birds or something.

Since I started building the enclosure I continued the build and finished building the frame that afternoon. The next step was to put screen around the whole frame but unfortunately the amount of screen on the roll of screen was a bit deceptive and although it looked like I had plenty to cover the enclosure, I only had enough screen to cover the top. I went to the hardware store and bought more screen and finished the screened enclosure on Sunday morning. It is rough and is not my most well made project but it does the job. I really can make things much nicer (see my other blog) and I will probably make a nicer one in preparation for next year after the mosquitoes are all either dead or dormant.

Screened Enclosure

One one side of the enclosure I put all of the dill that I have left (I’ll need to buy more) and on the other I put a bunch of dead sticks in a pot of dirt so the caterpillars have somewhere to form their chrysalis. I probably need to provide an easier way for the caterpillars to get from the dill pots to the ground and will do that in the morning tomorrow.

Anyway, back to the story. On Monday when I went to water the dill I found another large caterpillar that wasn’t there a few days earlier. Since the dill was in short supply before my mom picked up these two pots for me I think the caterpillars moved on to the parsley. Now I have six caterpillars back. I really hope to photograph the chrysalis and the emergence. We’ll see if I manage soon enough. For now I have some more interesting pictures to share.

Black Swallowtail Caterpillar Exposing Osmeterium

This caterpillar was very touchy. I didn’t have to touch it at all for it to expose its osmeterium. All I did was move the parsley pot and it reared up and told me to get away from its dinner! I rather like this picture but this one was a rather potent smelling one!

Black Swallowtail Caterpillar Molting

I found this one changing his suit. The half a little to the left of the middle seems to be a bit translucent and one of its feet is missing. I am not sure what happened to it but it seems to be okay since it is still alive and has almost eaten an entire dill plant by itself. I made him a prosthetic foot for the next picture using the clone stamp tool in Photoshop Elements.

Black Swallowtail Caterpillar Molting

Herb gardening seems to be one of those things that many people have at least attempted. Sarah and I have a potted herbs scattered throughout the back yard. Parsley and chives in the corner and thyme on both sides and basil between the blueberry bushes. Chocolate mint, spearmint, pineapple mint and orange mint near the house that some of which escaped the confines of the pot in which it was originally planted that needs to be majorly cut back. More thyme on the patio beside the rosemary and lastly dill. Dill is the only herb that we have in our back yard that I do not think we have ever used. So why do I still plant it? Well… it smells good and the flowers are attractive and the most important reason is to feed the caterpillars.

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Black Swallowtail Caterpillar (third instar?)

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Black Swallowtail Caterpillar (late third instar?)

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Black Swallowtail Caterpillar (fourth instar)

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Black Swallowtail Caterpillar (fourth instar?) Self Defense

This is the second or third season that I have treated this species of caterpillar to a delicate meal of fresh dill. I really enjoy planting something for the black swallowtail uses as its host plant. Call me a nerd if you want but I’m going to continue planting dill for as long as I can just so I continue to have visitors. The eggs hatch too fast and I can not say that I have ever seen one (I’ll keep looking though). It seems like one day the caterpillars are not there and then the next I have 4 of them. I guess I will have to look harder next year. I also have to plant more dill for reserves next year if the numbers keep increasing. Last year I had two or three caterpillars all year and this year I have six of them all at once. Sarah, Jen and I have come up with names for them Steve (original), Capulet, Montague, Buster and I don’t remember the rest. Hopefully I can keep them all fed.

I would really like to photograph the egg, earlier instars, cocoon and emerging process so that I have pictures of all stages of development. I may try to photograph the cocoon and emerging process this year. The caterpillars are sneaky though. They eat their fill and then while I am at work they journey far from their feeding ground to pupate. I might try to provide them with tempting pupating areas so that I can try to get the pictures of those stages.

Just in case you are wondering, the labels under each of the images above have in parenthesis third or fourth instar. An instar is a phase of development between molts. I made a guess as to which instar each caterpillar (I have six of them but only four are pictured) is in by measuring the length of the caterpillars and using the information about average instar lengths found on ButterflyGardeningAndConservation.com.

The last image is what the caterpillar does to try to ward off predators. I discovered this last year when I accidentally bumped into one of the caterpillars while moving a dill branch to get a better picture. It is called an osmeterium (Dictionary.com: 1. a glandular process on the first thoracic segment of many caterpillars that emits a noxious odor to ward off predators; 2. An eversible glandular sac on the first thoracic segment of many caterpillars that secretes an unpleasant-smelling substance to ward off predators.). I lightly touched its butt once or twice to encourage the defense mechanism so that I could show what it looked like. Fortunately for me the osmeterium doesn’t emit a smell particularly horrid and fortunately for the caterpillar I’m not a predator and I didn’t eat it. Also, I did apologize to the caterpillar for touching its butt.

Since it’s 2:00 A.M. I’m going to go to sleep instead of continuing to write because I could probably go on for another hour or more. I bid you adieu.