Abstract.Males of the caddis flyAthripsodes cinereus(Curtis) (Trichoptera: Leptoceridae) swarm above the water surface of lakes and streams. Females enter swarms and are pursued until grasped by a male. The pair couple their genitalia in the air, and then the male alone flies the pair to the shore where they settle and complete the copulation. About 8% of the pairs (totaln= 384 pairs) dipped in the water soon after the coupling manoeuvre and about 25% of those then separated. Males in dipping pairs (n= 13) were on average smaller and relatively older than the males that successfully carried their mate to the shore (n= 54). No differences were found for flight muscle ratio (weight of flight muscles/total body weight) or relative load (total load/flight muscle weight). Males were larger than females (wing length), though typically female Trichoptera are the larger sex. Large male body size inA. cinereusmay be an adaptation for flight during pairing; i.e. larger males are more likely to be able to carry larger loads.