ChefDean wrote:It's not a really tight mesh, so it's possible that a bumblebee could have forced it's way in, I'm leaning towards the small carpenter bees just because we had so many this spring. They ended up being the main food source for many of my plants, with more than a few Sarr pitchers having (estimated) more than 50% of the mass down their gullet being those little guys.
Not that it really matters in the wider context here, and I could be wrong, but I wonder if you may be confusing carpenter bees with a smaller type of bee. Carpenters are nearly indistinguishable from most bumblebees common in TN in both size and appearance, the main difference simply being whether their abdomen is smooth (carpenter) or fuzzy (bumblebee). Mine fill up with what looks to be mainly sweatbees and hoverflies, but I've never looked super closely so it may be at least partially another type of small bee instead like mason or miner bees. The only sarr I've ever had catch a carpenter or bumblebee was a rosea x flava hybrid with a huge mouth, and it stands to reason a carpenter bee would have no trouble nor qualms about just chewing its way out of a trap since that's, well, what they do best.
I found this quote from Mike Wang interesting:
Here in Northern California, we rarely have insects or other animals pollinate Sarracenia flowers. Honey bees, bumble bees, and other insects are frequently found in the flowers, but for some reason, they don't end up pollinating them-probably because of their size.
However, if a hummingbird finds your plants, they're very effective at pollinating Sarracenia flowers. Interestingly, they only pollinated S. oreophila and a tub of flavas-perhaps nothing else was in bloom at the time. In the past 15 years, this has only happened once-outside of the hummingbird incident, my plants never produce seeds without hand pollination.
That said, I'm also seeing several people, including earlier in this thread, saying they get natural pollination in the UK (which doesn't seem to have any Bombus species in common with Sarracenia's native range) and one Australian report posted here a couple months back, though in that case the flowers were apparently much smaller than usual which I imagine would have made pollination by smaller bees more possible. Additionally, assuming the introduced populations of S. purpurea in the UK are reproducing by seed then they must be getting pollinated by something. Either way, it's just strange that some people would be getting consistent natural pollination while others never do, even in the same geographic regions. For my part, it looks like I may have as many as 2 out of 5 flowers pollinated, but I could be mistaken and it be none as well.
I also wonder if some of the pollinators that are being assumed here (carpenter bees, smaller bee species, flies, etc) are just being assumed to be doing the pollination since they're present on/near/in the flowers, but in reality aren't actually performing the pollination and instead it's being performed by certain species that may or may not be among these.
Anyway, this obviously isn't really a discussion for this particular subforum. I just had no idea that natural sarr pollination was such an unsettled topic, and apparently completely hit or miss for different people even in the same regions. I'll postulate that it may be due to a presence or lack of one or more specific pollinator species, which would explain a lack of pollination even inside known pollinator's ranges and when other types of bees are present, so long as those particular species simply weren't present at that specific site. In addition, I'll add what was said here to satisfy pollination in the UK in particular, that being that pollinating species may be limited but not necessarily to Bombus species present in Sarracenia's native range, and they may instead include other species, Bombus or otherwise. There's really no practical way to test this on a large scale without widespread, geographically-distributed cooperation though, so I'm in no way making a conclusion here, just stating that that's my hypothesis at this stage.