These beetles have extremely flat bodies. This body shape allows them to crawl into packaged foods to eat, live and reproduce. It only takes them about 3-4 weeks to grow from baby to adult and an adult Merchant Grain beetle can live up to 3 years. Merchant Grain beetles can be found all over the world and can live in cooler climates. Once confused with a kind of beetle that does eat grain, the Merchant beetle was scientifically re-categorized, but the name stuck. These beetles get their name because they were commonly found on merchant ships, hiding in organic cargo.