Lee and Susan both found, as I have, that the best enemy of rats is the dog. I don't have city rats (Rattus norvegicus) here in the country, but there are wood rats, which are a bit smaller with furry tails. If I knew what part of the wiki to post it on, I'd scan a slide I took a few years ago. I came outdoors one morning to find that my Malamute bitch, then 3 years old, had dug and pulled up 30 feet of flexible perforated drainpipe that had been buried across a terrace, about 4 inches below the surface. She had torn this tough plastic pipe into 3 or 4 pieces in order to catch and kill a wood rat that had taken refuge in the pipe. Plants were strewn hither and yon. I took a deep breath and walked back inside to get the camera. There are few tree squirrels here, and only the native species, the eastern gray squirrel not having made it this far from the city yet. They're so rare that when Koshka caught one, she sneaked away with it, apparently fearing that it was some sort of cat and I would punish her for killing it. I had to explain to her that squirrels were fair game. Chipmunks are a problem among the bulbs as well, but they don't go far from the trees, fearing the dogs and numerous feral cats. The big problem in bulbs is field mice and voles. The other day I talked to a state pest control officer about them and was told that the only effective control was poisoned grain, and that this is hard to obtain. I knew about it but never used it because Koshka was an omnivorous forager, but now she has died at a ripe old age, and my present dogs don't forage as she did. I'm going to contact a pest control company to see what I can get against these rodents, so I can grow crocuses in the borders again, and not have to cover my most precious pots of crocuses with wire mesh caps in the bulb frames. Jane McGary Northwestern Oregon, USA