Aggregation and sexual attraction in Carabus – a field experiment

Individuals need to find both suitable environmental conditions and mating partners which might be especially difficult for solitary species. Here, we experimentally studied the role of olfactory cues in attracting conspecifics in several forest-dwelling Carabus species. We considered two possible ways of attraction, general aggregation and sexual attraction. In a field experiment we used single male and female beetles as baits in dry pitfall traps and compared the catches of these traps to those in empty ones. Depending on the species, we found suggestive evidence for aggregation behaviour and/or sexual attraction. Our study highlights that olfactory cues play an important role in Carabus but the underlying mechanisms remain to be studied.