I was trying to pay attention to the tour. We were at the Shaw Nature Reserve for the 2026 Grassland Restoration Workshop and learning about some great prairie and woodland restoration projects. I really was trying to stay tuned in. Unfortunately, I couldn’t stop watching carpenter bees steal nectar from penstemon flowers.

Both the foxglove penstemon (Penstemon digitalis) and the carpenter bees (Xylocopa virginica) were all around us in big numbers. The bees were very active in their visits of flower after flower. Clearly, the nectar was worth acquiring.

If you’re familiar with penstemon flowers, one of their key characteristics is their tubular flowers. I often see pollinators of many kinds flying or squeezing their way into those tubes to get nectar, exiting again with pollen stuck to their bodies. The architecture of the flower is well-adapted to facilitating pollination. Of course, that only works if the pollinators follow the rules.

What the carpenter bees were doing was landing on top of the flowers and using their mandibles (~teeth) to cut two little slits in the base of each blossom. They’d then stick their tongues through those slits and access the nectar directly. Subsequent thieves visiting the flower used those same access slits and stole more nectar. Those other thieves included lots of carpenter bees, but also some bumble bees and honey bees, who seemed more than willing to use the same shortcut.

Carpenter bees are known for this behavior, but they’re not the only ones. Bumble bees and honey bees, along with other bee species, sometimes do this as well. In some cases, they’re probably doing it because their body size or tongue length doesn’t give them any other way to get to the nectar. In other cases, I’ve seen some bees going about nectar acquisition legally and others (of the same species) taking shortcuts.

While half listening to our tour guide, I saw hundreds of penstemon flowers being robbed by dozens of carpenter bees. Bumble bees and honey bees appeared to be following the carpenter bees’ example as well. Not once did I see any pollinator insect go in the front door and pick up/deposit pollen. I’m sure it happened – I just didn’t observe it.

Nectar thievery is common but I don’t know of any examples of plants that are struggling because of it. My guess is that there are enough pollinators playing by the rules that the cheaters don’t have a major impact on seed production, but I’d be interested to hear from anyone who knows differently. Either way, I guess it’s an admirable adaptation on the behalf of the insects and, apparently, a big distraction for tour members who notice it happening around them. Apologies to our tour guide for my inattention.