Outdoor Pest Control - Getting rid of voles

Voles appear to be eating all my bulbs over the winter (small 1/2" diamter tunnels). I tried just about everything, but can't seem to eliminate them or even some. I've tried the hav-a-heart traps, but nothing enters. I tried glue traps with walnut in center (nothing yet, but has been cold so think glue hardens too much), mouse traps, rat and mouse poison.
I caught something once and turned out to be a shrew. Unfortunately, this is not a bulb eater.


Any idea on what I can use. I would love to just use some sort of bait, but all I can seem to find is the rat and mouse bait/poison. Not sure if this will work on voles as well.

Any rodenticide containing Warfarin, an anticoagulant which causes internal bleeding, will cause the voles to bleed to death.

I was told the voles eat grubs, so in order to get rid of the voles and moles you need to eliminate their food source. The is an all natural product called Milky Spore powder. The labor is time consuming because you have to divided your yard into 4 foot squares and put a tbsp in each corner, but this lasts for 15-20 years and you only have to do it once. It is also supposed to be good to get rid of Japanese beetles. The best part is it is non-toxic, so your kids and animals won't be harmed by it. The best price I've found is on Amazon.com.

Monroe, as I understand it, voles are vegetarians and moles are meat eaters. Part of being effective with these critters is to id the type of foraging catagory they are so you can use the appropriate methods. Here's some helpful info on the difference between voles and moles.

Voles:
http://www.volecontrol.com/voles.html

Moles:
http://www.ianrpubs.unl.edu/epublic/pages/publicationD.jsp?publicationId=92

These short videos are great for tips on setting the traps.
http://www.molepro.com/products/instructional_video_residential.htm

Newt