Papilionidae: Swallowtails and Parnassians - Family Spotlight

Added: 2026-05-05

[00:00:00]It's really not hard to convince someone that giant beautiful butterflies are worth saving, but most people just don't really know much else about them outside of their pretty colors. I mean, if you're a swallowtail fan, prove it. Name three of their albums. Welcome to the insect spotlight project, a channel dedicated to shining a light on insects, spiders, and any other creepy crawlies that get left out of the ecologic spotlight. Today, we're talking about the family Papilionidae, better known as the swallowtails, and also the Parnassians. Papilionidae is a family in the order Lepidoptera, the butterflies and the moths. So, if you're looking broader look at all of Lepidoptera, you can click that link above. The name Papilionidae actually comes from the Latin papilio, meaning butterfly or moth. So, right off the bat, that should tell you this is a pretty important group. Now, most people know the Papilionidae as the swallowtails, but this is incomplete.

[00:00:59]The Papilionidae is more accurately the swallowtails and the Parnassians, making up the subfamilies Papilioninae and Parnassiinae, respectively. But, this is also technically incomplete. There is a third subfamily in the Papilionidae, the Baroniinae, but there's only one species in this group, hence why it isn't talked about as much. And calling the family the swallowtails, Parnassians, and Baronia brevicornis just doesn't have the same ring to it. There are over 600 species described in Papilionidae with a worldwide distribution spanning all continents except Antarctica. However, most of their diversity is going to be in the tropics. I talk about how to distinguish butterflies from moths in my Lepidoptera video. So, for now, let's just focus on how to distinguish Papilionidae from other families of butterfly, butterflies being the superfamily Papilionoidea. Although it is not a shared trait across all of Papilionidae, and it's not even a shared trait for all the swallowtails, despite the name, the long tails at the back of the hindwing can be a pretty dead giveaway for a good chunk of this group.

[00:02:05]But, butterflies in other groups can also have tails, so don't rely on this too heavily. Papilionids also have all six legs visible and well-developed.

[00:02:14]This is important because another common family of butterfly, the Nymphalidae, have reduced forelegs. So, you can immediately distinguish between the two there. If you're a nerd, you can also look for the epiphysis. The epiphysis is a movable spur on the back of the foreleg tibia. Papilionids use it to clean their antennae. Now, when it comes to the butterflies, this structure is only found in the Papilionidae and the Hesperiidae, the skippers. So, it's a pretty distinctive trait. The problem is is it's very hard to spot even with a photo. Papilionids also tend to be bigger. I mean, you can't use this as a definitive characteristic. There are some pretty big butterflies in other families, and there are some smaller Papilionids, but it's still a helpful thing to keep in mind. In fact, the largest butterfly is a swallowtail.

[00:03:02]Queen Alexandra's birdwing can have a wingspan of up to a full foot, the females at least. The males are a little bit smaller. Color is usually not a great distinguishing characteristic for the Papilionidae, as they come in all colors of the rainbow. In fact, they're considered to be one of the most color-diverse families in all of Lepidoptera, showing the greatest variation in structural coloration, which is using microstructures to control light refraction in lieu of pigments. Even within species, you can often find various different color morphs. However, in the Parnassians specifically, they'll often have orange eye spots or other markings, which can help point you in the right direction from the get-go. And like all the other Lepidopterans, Papilionids are holometabolous, meaning they have a complete four-stage metamorphosis, going from egg to larva to pupa to adult. As with many Lepidopterans, the Papilionids lay their eggs on the host plants in which the caterpillars will feed. Sometimes, this is done in small groups, but oftentimes, the butterfly will just lay one egg at a time and scatter them around nearby plants. This way, they don't all get gobbled up in one go by a lucky predator. Oftentimes, the eggs will hatch in just a week or so, but this is certainly not true across all species.

[00:04:19]For example, many Parnassians live in cold alpine habitats, and this comes with its own set of challenges, one of which being harsh winters. So, to get around this, many of them will overwinter as eggs. Kind of. The larvae are actually fully formed, but they stay within the egg for protection from the elements. The chorion, or eggshell, is thickened to further help protect the larvae. And this is not, "Oh, it's a little brisk today. Good thing I'm wearing my eggshell jacket." These larvae are under the snowpack, and the snowpack is actually a benefit to them because it protects them from the even harsher winds. The winters in these mountainous areas are no joke. But, it is not just the elements that Papilionid larvae have to overcome. There are plenty of natural enemies awaiting them.

[00:05:07]Like in other Lepidopterans, parasitoid wasps and flies are a big hurdle for the Papilionid life cycle, laying their eggs on or inside their host, where the larvae will hatch and feed, eventually killing the unlucky victim. You can find parasitoids of Papilionid eggs, Papilionid larvae, and Papilionid pupae.

[00:05:26]And even if they remain unparasitized, they still have to avoid predation. Ants will happily carry off a Papilionid egg to their nest, and the caterpillars are basically just squishy sacks of fat and protein. They've got broad appeal. If it were up to the swallowtail or the Parnassian, they would have an unexciting life of munching foliage, not going very far and growing fatter until they eventually pupate into their adult form. But, as many of us can attest, just hoping to be left alone is not enough in this harsh reality.

[00:05:57]Evolution demands strategy. And so, like everything else in nature, the Papilionids have their own strategies for survival and prosperity. Like pretending to be bird poop.

[00:06:08]Look, beggars can't be choosers. If it works, it works. You got to respect the game. But, this is not the only mimicry found in the Papilionidae. Some species will have large eye spots, seeming to mimic snakes, and they aren't limited to one strategy, either. Some groups will start out as bird poop mimics, and then become more snake-like as they get some size on them. Aposematic, or warning coloration, can also be found in the Papilionidae, using bright colors and patterns to warn predators of their toxicity. But, perhaps the most interesting defense in the Papilionidae is the osmeterium. The osmeterium is a structure unique to Papilionid caterpillars, a brightly colored, fleshy organ that pops out of the head when threatened and releases a foul-smelling odor, providing both a visual and olfactory surprise, and hopefully warding off a would-be predator. And yes, this is the inspiration for Caterpie's horn. And if all of these defensive strategies are enough in the caterpillar's quest for survival, they will pupate. Papilionid pupae are normally brown or green, and you can find them on stems, bark, or even on walls, held in place by a silken girdle.

[00:07:18]This is also the stage in which many temperate species will overwinter, with those alpine Parnassians being a notable exception, of course. After a week or two, or once spring comes around, the adult Papilionid will emerge from its pupae and pump up its wings to prepare for its first flight. Adult Papilionids don't just mate and die off, but they're not going to stick around that long, either. They'll persist for a few weeks or so, feeding on nectar to keep their energy up and puddling to get all the minerals they need. Puddling is a strategy in which butterflies will gather around mud puddles and other damp areas to lap up salts and other essential minerals. Uh they're also attracted to urine, so a legitimate strategy could be to loop back to the spot in the woods you peed at and see if any rare butterflies came by. Papilionid mating can be a fun spectacle, with the males chasing after the female and diving and looping after her, but this can be hard to differentiate at times from males fighting. Male Papilionids can be territorial and will chase off rival males. Like many other insects, Papilionids will use pheromones to identify potential mates. If it's a match, they'll link up butt to butt, where the male will transfer a spermatophore to the female. This is a package of sperm and nutritive compounds to aid in egg development. Now, many Papilionids can mate multiple times, but some Parnassians and some swallowtails will create a mating plug called a sphragis to prevent further mating attempts. But, sphragis or not, the cycle continues. Now, there are some swallowtails that can come into conflict with us. Eastern giant swallowtail can cause significant defoliation on young citrus trees, but on more mature trees, their damage is mostly negligible.

[00:08:59]They're a native species to the US. They have plenty of natural enemies keeping them in check, so it's not really that much of an issue. The lime swallowtail seems to be the more significant citrus pest. It already needs to be carefully monitored in its home range of Asia and Australia, and it's since colonized the Caribbean and is making its way up through Florida. So, it's establishing itself as an invasive species. But, for the most part, we love our swallowtails.

[00:09:24]They liven up our natural spaces with pops of color, and they pollinate our flowers as they move between blooms. Not to mention, caterpillars pass on more plant energy than any other animal taxon, so they are the backbone of many avian diets. So, if you're not going to do it for the butterflies, do it for the birds. And by it, well, let's just say plant native. Native insects need native plants that they evolved side by side with. They cannot make use of a plant from halfway across the world, usually.

[00:09:56]So, look up what plants are native to your area and take it from there.

[00:10:00]Homegrown National Park is a great resource for this. Also, butterfly poaching is rampant in the swallowtails.

[00:10:06]So, if you want a pretty framed butterfly, please make sure the seller is operating legally and ethically. A lot of these vibrant species are already endangered from intense habitat loss in their tropical homes. So, let's not add to their destruction. Habitat loss is the real threat. So, seriously, plant native. But, anyways, thank y'all for listening. And if you like the content, please remember to like and subscribe to keep up to date with future videos. And if you have any favorite species from this group, which I know some of you do, or any fun facts that I missed, please leave them in the comments below. I always love hearing about it. Peace, y'all.