Pipevine Swallowtails: More Where That Came From!

Over the past ten days since we found our first Pipevine Swallowtails (Battus philenor hirsuta), we have been actively searching for more to add to our collection and have hit the jackpot!

---

We first found the California or Hairy Pipevine Swallowtail (Battus philenor hirsuta) last Saturday on 6/18 at Tilden Regional Park and it was a pretty amazing day -- to not only really see this amazing species for the first time but also to collect so many of them. To kick it off, we had found a total of 14 caterpillars and three clusters of eggs (for a total of 53 eggs) -- more than enough to ensure success in rearing them and probably even enough for a healthy breeding stock in the future. We thought for sure we had drained the place of its stock, at least for a while. . .

But the following week (last week) and this week, we proved ourselves wrong and completely outdid ourselves. From being completely nonexistent among our collection of insects, the Pipevine Swallowtail now firmly stands as one the species with the most individuals we have reared at a particular time, a close second to the more common Anise Swallowtails (we have raised thousands of the latter over the years, believe me!). And all of this in less than two weeks.

You see, we don't have actually any pipevine plants available at home for us to feed our caterpillars. So, every 2-3 days we have to head all the way back up to Tilden Park to pick a few leaves. We could also pick leaves at the Botanic Gardens (part of Tilden), but that would just be a downright violation of the hard work the gardeners have put into planting it and would also destroy the appearance of the plant for visitors. Anyway, because we have to visit the pipevine so often, we have every opportunity to nab any more caterpillars, eggs, or even butterflies that may show up (I doubt we are the only ones looking for them!!). And that's exactly what we did. 

​On Tuesday 6/21 when we went to pick leaves, we found two more pipevine plants that we had not seen before and reaped another 14 caterpillars -- almost all of which were fifth instars -- and doubled the number of caterpillars we had. In addition we found not three, but four more clusters of eggs for a total of 71 more eggs -- more than doubling the number of eggs we had. And to top it off we found two chrysalises off to the side of one the vines. 

By the time we returned on 6/23, we didn't expect to find many more unless we discovered yet another new vine. Plus, almost all of the caterpillars we had found had been fifth instars with a whole bunch of them already wandering around and ready to pupate at home so we expected that any of the ones we missed were probably also wandering and/or already chrysalises. This would make them a pain to find them. However, on the same pipevine we found the majority of our caterpillars on 6/18, we won another 10 caterpillars. Not to shabby . . . 

On 6/25, we wanted to try something different. California Pipevine (Aristolochia californica), of course, is native to the region so in theory one should be able to find it growing in the wild in the appropriate habitats. While it is true that the vast majority of natives are becoming increasingly scarce and can no longer be easily found in their natural habitat, we thought it would definitely still be worth a shot to try to find more of the stuff in other natural areas or parks. After all, we found it growing in the wild at Tilden. So, after some time, we decided to head out to Canyon Trail Park in El Cerrito.

What led us to Canyon Trail was pretty simple. Pipevine Swallowtail populations are very unstable to say the least, because they are limited to a single host plant. In Albany, where there is not a single pipevine, they are no where to be seen -- not even a stray butterfly taking a visit. In Berkeley, the swallowtails don't exist either except in rare places with pipevine such as Tilden. So, the fact that there have been sightings of Pipevine Swallowtails in El Cerrito (we believe that we even saw one there ourselves) is a strong indicator that there is pipevine. And, unless it was simply growing in someone's backyard, the best place to look would be in its natural habitat and we thought Canyon Trail was a decent contender. As an overview, Canyon Trail Park is a very small, out-of-nowhere (isolated) park with only a few short hiking trails. It actually even has a playground and picnic area and a school next to it with tennis courts and such so it's not completely a nature area. But we still were willing to give the place a chance.

However, immediately when we got on the trails at 7:30 PM that day we realized with sinking hearts that the place might not have been the natural habitat we had hoped for since there were massive amounts of invasive ivy (Hedera) vines growing rampant. Not to mention invasive wild fennel (Foeniculum vulgare) in some areas. After searching the trails for half an hour to no avail, we were almost ready to give up. It seemed that the only vines there were were ivy and bramble (Rubus ursinus), growing along literally every part of the trails and dominating the entire ecosystem of the park. 

By the end of the half hour, the one place that we hadn't looked was a small elevated clearing off the very end of the main trail. The bottom portion of the area is covered in dried grasses and occasionally dotted with little shrubs and trees like Coast Live Oak (Quercus agrifolia). Near the top, there are some tall trees like California native Redwoods (Sequoia sempervirens) and what appeared to be more vines. Looking up from the trail, they looked a lot like bramble, but we took a chance and painstakingly climbed our way up to take a closer look. Here, to our incredible delight, there was California Pipevine mixed in with what was indeed a lot more bramble and ivy. The pipevine was everywhere along the ground, a much larger plant than any of the ones at Tilden though it was in a lot worse condition. Nonetheless, we found three more caterpillars here to add to our collection. While this was less than we had expected for how much of the vine there was and how many of the leaves appeared to have caterpillar holes bitten into them, it was a whole lot better than coming back empty handed after such a long trip. The next day when we came back here during the day (2:00 PM) we even found a female butterfly as well as some nice looking grasshoppers. 

By today, we were back to Tilden. Even though the chances of finding any more caterpillars was even lower than before (almost all of the fifth instars we have at home are beginning to pupate), it had been a week and a half since our first visit on 6/18 so we still had a good shot for finding some freshly laid eggs. After searching for well over an hour, we gathered our biggest and most insane find yet in terms of numbers: a total of 5 more egg clusters for a total of 67 eggs, 2 clusters (of 14 and 21) of young caterpillars that must have hatched from eggs we missed previously, a lone second instar caterpillar, and another chrysalis. 

So, the question we all want answered now is: What in the world is our total? 

In total (discluding any that may have later died) we found twelve egg clusters for 191 eggs, two clusters of gregarious (young) caterpillars for 35 caterpillars, 43 solitary caterpillars, and 3 chrysalises. A grand total of 272 individuals we are or will be rearing this summer, and all in just ten short days. I guess, the final moral of the story is "if you want something, get out there and look!"

- Brian