Pediasia truncatellus is a species of moth in the Crambidae family. It is found in Fennoscandia, northern Russia, the Baltic region, the Czech Republic and Canada. The wingspan is 25–30 mm. The forewings are dark reddish-brown, with a darker basal half. The hindwings are dark smoky. Adults are on wing in June and July in northern Europe and in June North America. The larvae possibly feed on Sphagnum species.