It was inevitable, I guess...
Following the success of the 'mystery' brassica in our garden and the abundance of Large White butterflies visiting the plant, there was always going to be a long game playing out through the remainder of the Summer and into next year.
A while back, as Our Lass and I sat outside enjoying an afternoon's sunshine, we noticed caterpillars heading for the hills, or at least across the path and up the wall of the house.
Over the course of several days, chrysalides appeared on the soffit boards all around the property, as this year's larvae pupated to prepare for next year's population of adult butterflies.
A few days after that, I noticed that a few of the chrysalides were missing, and I presumed that they'd been discovered by a predator and eaten. To be honest, I couldn't think which of the birds visiting our garden would have the ability to do this, but I let that pass. Possibly wagtails?
Later still, I saw that many of the chrysalides had what appeared to be tiny balls of fluff alongside them. This did puzzle me, as I couldn't figure out what was going on.
Then, yesterday, whilst idling looking through the excellent 'Bugs Britannica', by Peter Marren and Richard Mabey, to find some information on bristletails, I spotted a photograph that nailed the reason once and for all.
A species of parasitic wasp had laid their eggs in the growing caterpillars and whose own larvae has consumed the caterpillars from within and then finally emerged from the chrysalides to pupate themselves. Gruesome, but that's how evolution works in the insect world.
So, yes, in a way the pupae were the victim of a predator, but not at all in the way I'd imagined. The unfortunate caterpillars had carried their assassins with them during their epic journey up the wall of the house.