The Chequered Lancer Plastingia naga and the Yellow Chequered Lancer Plastingia pellonia are the only two Plastingia species in Singapore. Both are forest species and like to rest in the shade of the undergrowth with folded wings. The only time they open their wings is to bask in the sunshine when puddling. The former is uncommon and the latter is rarer.
I have yet to see the Yellow Chequered Lancer but have encountered the Chequered Lancer on two occasions at Dairy Farm Nature Park and Upper Seletar Reservoir Park. Unfortunately they were too quick for me to get any photographs.
Over the year, there were several sightings of the Chequered Lancer along the forest trails at MacRitchie Reservoir, which I missed. So it was third time lucky when I came upon a tame individual resting by the side of the trail on 1st Sept 2022.
What made this encounter special was getting photos of the top view and the side views of their full wing spread. I cannot find any photos of the Yellow Chequered Lancer upper wings but I read that both look similar with the white spots of the Yellow Chequered Lancer appearing larger than the Chequered Lancer. Whereas the underside is very different. The markings of the Yellow Chequered Lancer are yellow while the Chequered Lancer markings are white, giving it a black and white chequered look.
Reference: Butterfly Circle Blog