I have found wire wastebaskets at the dollar store with very small holes and have had no losses so far. My voles must be from the shallow end of the gene pool, since they have yet to figure out that the cage is open at the top. Some time ago an online biologist suggested the following--warning, sqeamish people should stop reading now. I have not used this due to too many cats, dogs, children and other indiscrimately oral types but: add Plaster of Paris powder to peanut butter, place in affected area and hope that none of the above mentioned creatures reach it before the mice do. It solidifies in the gut causing a blockage and death. If I had rare crocus I might use it if all else failed. This is as indiscriminate as poison bait and much more appealing to rodents but I know some of you are not plagued (blessed?) with so many potential innocent victims as I am. Perhaps if the bait was hidden in a small-mouthed container that was nailed down and inaccessible to hungry dogs? Another plus is that it is unlikely to harm a predator who eats the carcass of the rodent, unlike poison bait. zone 8, Sierra Nevada foothills, the early tazettas have sprouted, slong with freesias and ranunculas. No rain, we must be way below normal in snowpack and water. Unusually warm.