Nesting behaviour of adventive Isodontia mexicana (Saussure) in Piedmont (Italy North-West) (Hymenoptera Sphecidae)

The biology and ethology of the solitary sphecid wasp Isodontia mexicana (Saussure) were ascertained in Piedmont. For the first time in this species and in the whole genus, social interactions between nesting females are reported and briefly illustrated. The most usual behaviours were: nest agregation, re-use and usurpation.