Are you sure the stems didn't rot and break off?

Small creatures looking for water? try putting out a shallow dish of water... and keeping it full.

We have an abundance of rabbits this year, and I too have noticed that the cucurbits which were sprawling have been chewed and even killed. The cukes growing on a trellis haven't been bothered. I've had to put a 2' high fence of chicken wire around the chard/beets/mustard greens because the rabbits chewed them to the ground.

I have a rather wimpy little plastic snow fence all around by garden to keep the dogs from helping themselves to the tomatoes. It has always worked for them, but the rabbits chewed through it. We have noticed that small rabbits can get through chain-link fencing.

Linda

My guess would also be a rabbit, they love to hide out in a vining plant patch like WMs, cantaloupes, cukes, and sweet potatoes.

Thanks everyone. I have to go with rabbits then. Although I have no idea how it would go in with my beds having a 3 ft fence around it I guess it founds it way somehow. Did not notice any new damage today

A stem cut off at the ground & left to lay is typical vole damage. They probably have a nest nearby, under debris or landscaping (or in a burrow under the vines). Put out a few mouse traps & you should catch most of them... pieces of dried apricot make great bait, since the scent attracts them. Left alone, they will multiply & become a more serious problem later in the season.