Look for the section "inheritance of sex". There are quite a few examples in the Natural History Museum including (I believe) a Silver-washed Fritillary with one half male and the other half f. valesina female.
Incredibly fascinating subject, I have Butterflies by E.B. Ford and Variation in British butterflies by Alec S. Harmer and had not gotten around to reading them, will have to make the time probably over the winter, like most there does not seem to be enough hours in the day.