NEOICHNOLOGICAL EXPERIMENTS WITH MASKED CHAFER BEETLES (COLEOPTERA: SCARABAEIDAE): IMPLICATIONS FOR BACKFILLED CONTINENTAL TRACE FOSSILS

Abstract

Abstract Laboratory experiments conducted with larvae and adults of the northern or southern masked chafer beetle (Scarabaeidae: Cyclocephala lurida or C. borealis) tested hypotheses that beetle larvae construct meniscate, backfilled burrows and that they are distinct from backfilled burrows constructed by marine organisms. Beetle larvae were placed in narrow enclosures with laminated moist, fine-to-medium-grained sand and allowed to burrow for several weeks. Beetle larvae did not create open burrow systems but instead excavated single open cells approximately twice their body width and roughly equal to their body length. Burrowing was accomplished by scraping sediment with the head and mandibles, consolidating excavated sediment into a ball, rotating 180° with the ball to the back of the cell, and packing the ball onto the posterior end of the cell. The beetle larvae produced vertical-to-horizontal traces that were straight to tortuous and composed of discrete packets of meniscate backfill. Adult chafer ...