Observation of fritillary egg laying is difficult as the eggs are very similar in color to the female's ovipositor. It has been seen that eggs may not even be laid after extensive enquiry by the female of potential egg sites. Females also prefer to lay eggs that are on firm ground rather than ground with loose plant matter. In outcrops eggs are laid in short vegetation next to limestone that offers good moss cover. In Bracken eggs are laid in groups in the midst of thick Bracken clumps. Dead Bracken litter is a popular site for egg laying, as well as moss and other decaying vegetation.[2] Eggs are laid in spots conducive to sun bathing,.... Oviposition The egg laying process begins when a female does low passes above bracken fronds and drop down when they find a suitable spot. Females will then crawl on the bracken littered ground and use their abdomens to probe for likely egg laying spots. Eggs are normally laid once a female crawls over a plant that can serve as a food resource. Eggs may also be laid without any area observation, and without any food plants nearby, as females have been observed to lay eggs within seconds of landing. False egg laying is also common.[2]
Wijngaard, Wopke. "Control of hovering flight during oviposition by two species of Bombyliidae." Netherlands Entomological Society (2012): 9.(無料公開のPDFファイル)