We used Cedar for my garden bed frames and I have noticed a remarkable decrease in unwanted pests, primarily SLUGS! I garden organically so this was a pleasant surprise. Also since the addition of Cedar Rockers on my deck I no longer have any pesky flies hanging around! Below is information I found on the internet:

Cedar is very popular, grown for their durable (decay-resistant) scented wood, most famously used in the construction of King Solomon's temple in Jerusalem provided by King Hiram, or Ahiram, of Tyre, Lebanon, circa 1,000 BC. The wood is also used for humbler purposes requiring resistance to weather, such as shakes, shingles, and outdoor furniture. Cedar wood and cedar oil is known to be a natural repellant to moths  hence hope chests were made of cedar when available.