The Hidden World of the Passionflower Vine
I love the passionflower vine! (passiflora incarnata) Beautiful flower, great nectar source, cool fruit. Yet I sometimes hear gardeners say that it is taking over their garden and they are going to pull it all out. Don't do it! There is a whole world of creatures relying on this plant and lots of treasures to be discovered.
Our passionflower vine world
Along one side of our driveway we have a spot passionflower vines have volunteered to grow. We put up a small section of fencing for the vines to climb on and let them go. They soon spread to the tree stump nearby, the yaupon holly bush, the horsemint, the path.... They were very happy. I developed a habit of looking closely at the vines every few days to notice the world created. Through the summer, I saw expected and unexpected creatures and learned a lot.
Our passionflower world in July.
I started to see gulf fritillary butterflies hanging around. Passionflower vine is their host plant. A host plant is the preferred plant for caterpillars of a species to feed on. Different butterfly species prefers different plants.
Gulf fritillary butterfly (agraulis vanillae)
Soon I noticed a few caterpillars. Mostly I saw the orange and black instar (Caterpillars come out of the egg very small and go through many molts, sometimes changing dramatically in appearance with a molt. Each "version" of the caterpillar is called an instar.) but I also found evidence of earlier instars.
The orange caterpillar in this picture just molted from the black "skin". These are tiny. You can see my huge thumb in the upper right of the picture for perspective.
Later instars - lots of them. Getting larger and larger.
And they are hungry. Numerous and hungry and large. Notice the piece of vine showed here that no longer has any leaves on it.
Here is our passionflower world in August. Many fewer leaves because the caterpillars ate them.
As I was looking for caterpillars I noticed there were ants on the vines. You can see the little black ants in this picture.
Researching this, I discovered that passionflower vines have a symbiotic (mutually beneficial) relationship with ants. Ants get a nutritious nectar from extrafloral nectaries (nectar sources outside the flower) at the base of each leaf. In return, the ants protect the leaves from insects that want to eat them (including our caterpillars). See article
Who knew the ants were part of this world?
Back to the gulf fritillaries. I started noticing many more butterflies around the plants. Some in pairs, as these on the driveway, some hovering around the plants and landing on the leaves.
Of course they were mating and then the females were laying eggs. They would try really hard to lay those eggs on the host plant, the passionflower vine, to give the newborns their best chance of survival - an immediately available food source.
I searched and searched for eggs and never saw any. But they were there! Just so tiny I missed them. They are about the size of a sesame seed. Here is a picture - though not mine because, as I said, I couldn't find any.... sigh....
The life cycle of butterflies is described as complete metamorphosis. In complete metamorphosis, the insect goes through four stages. In each stage it is anatomically and physiologically completely different from itself in other stages.
Watch this video for more information.
In our passionflower vine world the beautiful flowers are blooming. These are intricate, colorful, delicate flowers that seem designed perfectly to transfer pollen onto bees and other pollinators.
And pollination results in fruit.
Interestingly, at least to me, all of the fruit disappeared. There were about 20 on the plants at different times, and I never saw one ripen, never saw any evidence of one on the ground. I wonder what came and took them away. In the spring, I will likely find new passionflower vines in unexpected locations.
One day I was looking for a chrysalis (they are hard to find! Well camouflaged.) and I saw something odd.
I took it inside to look at under a loop and do some research. Upon a closer look, it looked even more odd. What is this neatly arranged tiny collection? I sent a picture out to some knowledgeable insect folks and asked friends on Facebook. Can you guess?
Well. Apparently stinkbugs (a shield bug) lay their eggs in a cluster on the bottom of leaves just like this. Pentatatomidae Euschistus sp.
The white things in the middle are the egg shells. The brown creatures huddling around them are the nymphs that came out of those eggs. Why do they stay in such a neat formation?
Amazingly, some stink bug species stick around after the eggs are laid to protect their offspring. The female stink bug will guard her cluster of eggs from predators. She'll continue this even after they hatch for at least the first instar. Wow!
I really really wanted to find a chrysalis. I finally did find just one. I know there were many more because we kept getting more butterflies. Doing some reading, I learned that caterpillars wander away from the host plant when they are ready to pupate. I never discovered where they went. Just one caterpillar wandered to our porch and became a chrysalis on a small overhang there.
This metamorphosis is an amazing process. Here are a couple of videos - one of the caterpillar becoming a chrysalis, one of the butterfly emerging from the chrysalis.
Finally, in October, we come to the end of this year's version of our passionflower vine world. Notice how empty the vines are of leaves. All of them eaten by the caterpillars.
And the yaupon holly and horsemint survived and bloomed, produced fruit and seeds. Don't pull out the passionflower vines mid season. Let them create a world for so many creatures. The other plants will survive and be fine because the caterpillars will take care of all the foliage.
I had so much fun this summer following the world created by this plant. I learned a lot! And we had beautiful gulf fritillaries all over the yard.