Question
I live in the small town of Coleville, Saskatchewan  Canada.

  My question is I have some kind of a slug that chews holes in the potatoes and tomatoes. The potatoes survive but the tomatoes go bad. The slug is about an inch long, greyish green color, no visible legs, two antenna on the head. When disturbed it pulls its head within it's self and shortens up to half of its size. What is this thing and how can I treat it.  

Answer
It definitely sounds like a common slug.

I, too, have had many heartaches over the damage slugs have done to my plants over the years.  I have tried everything including beer traps, diatomaceous earth, homemade traps, and copper.  I must admit that I抳e had moderate success with the beer, but it would evaporate each day and got expensive to maintain.

I am happy to say that I抳e finally discovered an effective deterrent.  It is a product sold by a company named Gardens Alive, and is called Escar-Go.  Although it is a pesticide, it is organic, and is therefore non-toxic to humans and pets.  It also stays active and solid even after a heavy rain.  Just sprinkle small amounts around each plant, and reapply every 10 days.  In case you抮e interested, click on the attached website and search for Escar-Go.

http://www.gardensalive.com

If the area is large, making this product impractical, try spraying the soil with an ammonia solution.  Mix one tbs. lemon ammonia and one tbs. of non-concentrated dishwashing liquid per gallon of water. You抣l need to apply this solution twice per week, and preferable in the early morning hours when slugs are most active.

Recent studies have also showed that slugs are deterred by coffee grounds. Many gardeners apply used coffee grounds to their soil as an organic amendment. These same studies have shown that plants with old coffee grounds sprinkled around them have 80% fewer slugs than those not treated. It also has shown that the coffee grounds kill young slugs. They suspect it is the caffeine, but they are still researching the actual cause and effect.

I hope this helps.  Good luck, and please write again if I can ever be of assistance.

Regards,

Mike