Richard South, The Moths of the British Isles Second Series… (1909)
“ Wherever colonies of two of the kind exist within visiting distance of each other, there, it appears, we may reasonably expect to find hybrids.From a number of cocoons collected in a Yorkshire locality for loniceræ, I reared, in 1907, a good many examples of that species, and also about a dozen six-spot specimens, which agree in colour with filipendulæ, but they have the vein-interrupted sixth spot and broad border to hind wings, as in hippocrepidis.The caterpillar (Plate 145, Fig. 4) is greenish, with black markings and some yellow spots, the latter chiefly on the hind edges of the rings. ”
