- Common Names: Gulf Fritillary, Passion Butterfly
- Taxonomic Name: Agraulis vanillae
- Host plant: Passion flower vines
- Habitat: Open, sunny meadows, and shrubby, disturbed areas
- Distribution: Southern United States, Mexico, Central America and northern South America (see a detailed map)
- Conservation Status: G5 (secure)
- Caterpillar Season: year-round
I was so excited to be able to grow tropical plants when I moved to Florida and passion fruit vines were at the top of the list. I purchased a plant, a pot and some soil and got all set up with my new Passion Fruit plant… Seconds later I had Gulf Fritillary butterflies laying eggs all over the plant. At first I was a little frustrated because I really wanted to grow passion fruit, but once I saw these crazy wild looking caterpillars, I was totally hooked. I could watch these caterpillars eat leaves all day – they are really amazing!
I noticed something about my passion flower vine – it had two strange knobs at the base of each leaf that would have a big drop of clear liquid on them in the early mornings.
After doing a bit of research, I discovered that these pores (called “extrafloral nectaries”) are part of a mutualistic relationship that has evolved between this plant and certain species of ants.
The nectar excreted by the plant attracts these ants who will (in addition to collecting the nectar) perform some important housekeeping functions for the plant such as cleaning the plant of fungal spores and eating the eggs and newly hatched caterpillars of the Gulf Fritillary butterfly along with any other small grazing creature that may eat the plant. (Thomas, 2007).
To counter the predation of ants, butterfly females will often lay their eggs on the very tips of the passion flower vine tendrils.
The caterpillars themselves are not defenseless either, they have evolved some very specific biochemistry that protects them and their bright coloration and markings serve to warn predators of this.
The passion fruit vine contains toxic compounds that prevent most insects and other creatures from eating this plant. The Gulf Fritillary and a few other species have evolved not only to tolerate this toxicity, but to use it to their advantage. They can absorb these toxins and store them making the caterpillars and adult butterflies as toxic to eat as the plant. (Raupp, 2016).
When tropical storm Elsa came through St. Petersburg, I decided to rescue the biggest caterpillar and give him shelter until he was ready to pupate.
When I brought him into the house, he was between 30 – 35 mm long. I fed him fresh leaves for about a week and when he reached just under 40 mm long, he began to pupate.
It was absolutely amazing to watch! He attached to the underside of his leaf and formed the classic J-shape. The gray-ish bulges on the sides where the wings will form emerged first.
He emerged sometime overnight about 14 days after forming the chrysalis and I released him (her?) almost immediately since I didn’t have any food to offer .
Minno, Marc C. Butler, Jerry F., Hall, Donald W.. 2005. Florida butterfly caterpillars and their host plants. Gainesville, Fl: University Press of Florida
Raupp, Michael J. 2016. Bugs in orange and black, part 2, beautiful but stinky: gulf fritillary, agraulis vanillae. http://bugoftheweek.com/blog/2016/11/1/bugs-in-orange-and-black-part-2-beautiful-but-stinky-gulf-fritillary-iagraulis-vanillaei?rq=gulf%20fritillary.
Thomas, Bob. Extrafloral nectaries, Delta Journal, The Times-Picayune, August 12, 2007. https://lucec.loyno.edu/natural-history-writings/extrafloral-nectaries.