in the deep, dark night something is feasting on my seedlings. the hardest hit box is elevated on a table with some copper tape around the edge (i thought it might've been snails) where half my arugula, lettuce and radishes are nibbled down to the dirt line. every night a few more seedlings are decapitated.

strangely enough, the radishes on the ground have been unmolested BUT their next door neighbors, the carrots are slowly being mowed down.

any ideas of what is going on? i was thinking of putting up some kind of netting, but how small would the holes have to be? would it work? how would i get into the plants?