New to slrs. What lens do I ?get?

I am learning photography, and I just bought the canon t1i with 18-55mm lens and the 55-250mm lens. I like to take close ups, flowers, insects etc. The closer the better. I like the small details. What macro lens would one recommend for a beginner? Also I like to take landscape, wildlife, etc. The 55-250mm still doesn't get me as close to the critters as I would like. I live in Alaska so the terrain can be difficult, it can be hard to get close to a moose for example.What would one recommend for this type of shooting. Another question, What about the cold and cameras and lens?