After writing about carnivorous plant issues on this site for the last decade, it’s always funny when unrelated discussions lead right back to the subject at hand. A week ago, the subject was on bee burn, where Sarracenia pitcher plants catch more stinging insects than the plant can digest, particularly at the end of the growing season. A little trip to the Texas Hill Country, specifically to the town of Wimberley, independently demonstrated why.
Shortly after the actual wedding ceremony was over, when everyone sat down with beverages of their choice, we found ourselves surrounded by paper wasps. They weren’t aggressive, but they were persistent, and gentle shooing didn’t do much to convince them to go elsewhere. They weren’t just going for open drinks, either: they were going for particular pieces of clothing or jewelry, and even particular shades of lipstick. After a few minutes of consideration, Caroline of Caroline Crawford Originals, official wedding jeweler and spouse of nearly 19 years to your humble chronicler, discovered that all we needed to do was set out a spare glass full of something sweet at each table, and the wasps left us alone to get a good drink of margarita sugar syrup or Sprite. In the process, we were making our own artificial Sarracenia without realizing it.
The explanation for the wasp invasion was easy. While larval wasps are enthusiastic carnivores, adults are nearly invariably sweet-tooth acolytes, with a diet mostly made up of nectar, honeydew from aphids and scale insects, and whatever other sugary treasures they can find. (That attraction to sweets applies also to more derived wasps such as bees and ants, which explains how you get ants.) To this end, the members of the angiosperms, the plant order comprising flowering plants, that don’t depend upon wind for pollination depend upon insects, and nectar is an extremely effective way to employ insects’ services. Between sugar and bright patterns visible under ultraviolet light, we have approximately 90 million years of co-evolution between insects and angiosperms, and all of the pitfall carnivorous plants use one or both to capture prey.
What’s going on now is the end of the wasps’ life cycle, at least involving these. Most paper wasps designate one female as a queen, and she promptly finds a spot in a woodpile or compost pile to spend the winter before reemerging in spring. The others keep going on as long as they can find food, but with local flowers fading for the year, the competition with solitary and gregarious bees and the occasional indigenous hummingbird gets intense. By the end of October in Texas, the few paper wasps that haven’t become food for birds, spiders, or praying mantises are desperate for any available food source, which is why they come running to uncovered soda, wine, or mead. Since wasps see mostly in ultraviolet light, they’ll also check out any item that fluoresces under UV in the hope of catching a spare bit of nectar missed by everything else, and most humans would be amazed at how many items of clothing, jewelry, or makeup pop under UV. Eventually, that runs out, and the few wasps that don’t die of starvation will die with the first serious cold snap. That cold snap arrives in Wimberley this week: the odds are really good that these wasps will be dead by the weekend, but as the political writer Charles Pierce says every Friday about dinosaurs, they lived then to make us happy now. And so it goes.