On Mon Sept 27th I wrote, 'In several hundred hours of searching I have yet to find a larva on a branch bearing anything more than the odd spot of (Sallow Mildew)', and even more foolishly questioned whether iris females cannily avoid sprays that might be susceptible to this mildew.
So, the following weekend I find three larvae on mildew-affected leaves / sprays... . This butterfly defies science, ecology and natural history, but is seriously good at stimulating theories.
Suffice it that there is a lot of Sallow Mildew around this autumn. I will keep a close watch on these larvae to see how they fare.
Incidentally, the locations of the (very) few wild larvae I am following this autumn have been recorded via a Magellan MMCX GPS (which works well in woodland). I have left no markers on the trees.