The eggs are laid in May and early June, in neat heaps on the underside of leaves of devil's bit scabious Succisa pratensis. In continental Europe a wider range of foodplants are used including Scabiosa, Lonicera, Cephalaria, Knautia, Gentiana, Primula, Digitalis and Plantago.

They are pale yellow when first laid, quickly becoming bright yellow, then turning to crimson, and finally to dark grey just prior to hatching. Usually all the eggs are laid in a single batch close to the emergence site, but in hot summers the females disperse after laying the main batch of eggs, and lay smaller batches some distance from the nucleus of the breeding site.

Females will oviposit on quite small scabious plants, with leaves appressed to the ground, but greatly prefer larger plants with lush leaves raised well above the ground, growing amongst fine grasses.

Females are burdened by the weight of hundreds of eggs, and fly only short distances. Males are very active on the wing, flitting rapidly, low over the ground in search of females, but stopping frequently to take nectar from a variety of flowers including buttercups, hawkbit, bugle, germander speedwell, milkworts, orchids and marsh thistle.  They also appear to be attracted to certain fungi - in 1985 I found over a dozen male Marsh Fritillaries which had become glued by their wings to the sticky surface of fungi at a site in north-east Hampshire.

The prenuptial process is brief, as witnessed by the following observation in late May 2009 : At noon I watched a male intercept a flying female, which immediately settled in the grass with her wings open. The male buzzed around her but made no attempt to copulate. The female then flew a very short distance, followed by the male which alighted beside her. This process was repeated 3 times until the female found a suitable blade of grass on which she settled with her wings outspread and her abdomen curved downward. The male approached from beneath and curled up his abdomen to make contact. The pair remained copulated in this position for several minutes until a gust of wind caused them to readjust, after which they crawled onto a nearby bramble leaf on which they rested with wings closed. About 2 hours later when I returned to the spot I found them basking with wings outspread. It is likely that the butterflies remain copulated overnight - I have often found copulated pairs at dusk, and on occasions when I have bred this species in captivity the pairs have always remained joined overnight and parted early the next morning.

If a male intercepts a female which has already mated, the female walks and flutters about on the ground amongst fine grasses, vibrating her open wings, whilst the male excitedly dances around her in a series of tight figure-of-eight movements. The purpose of this activity seems to be to "imprison" the female while the male showers her with pheromones, but the unreceptive female simply sits tight until the male gives up and flies away.

In overcast weather conditions, butterflies of both sexes bask for long periods on low foliage, or in rabbit-scrapes or other depressions. Overnight, or in wet weather, they hide themselves deep within tussocks of grass.

Population dynamics