Larvae of fireflies (Coleoptera; Lampyridae) feed natural and greedily of various species of terrestrial mollusks including slugs. Although this antagonistic relationship has been documented in countless species of Lampyridae, in the case of the genus Cratomorphus Motschulsky, 1853, its predatory role on these land mollusks is unknown. The aim of the study was to record for first time a predatory event of Cratomorphus signativentris larvae on the Cuban Slug (Veronisella cubensis). Similarly, some comments are made on larvae and adults of C. signativentris studied, as well as a comparison of food preference in this genus.