The year was 1999 plus or minus a year, the site was a few miles from Asheboro, NC. I don't recall the season, but it was warm, and there is definitely a chill there in the cold seasons, so I assume spring or summer. It was about half an hour after sunrise; I was walking my dog. I would occasionally carry my camera "just because ..."
I saw these two acting strangely on the surface of the wooden shed. They actually attached themselves, then went into freefall. They twined around each other, and then a moist pouch was extruded below them. White froth was present but in moderation.
I don't recall what exactly happened after that. They remained suspended for some time, and the likeliest thing is that I left them to their passion.
So, can someone identify the species?
How big are they? Limax maximus mates dangling from a mucous thread like that. Adults are about thumb sized.
I would have pegged them as Limax maximus because of that acrobatic behaviour. Haven't seen them that colour before so they may be something else. The ones I see in my garden here in southern Australia are usually more grey and black.