The sawtoothed, foreign, and squarenecked grain beetles share this same description. The female lays 22-190 white, shiny eggs either singly or in small clusters in crevices in food material over several months. The eggs hatch in a few days. The larvae usually molt 3 times and usually construct a pupal cell or cocoon from food particles held together with sticky oral secretions. There may be as many as 6-7 generations per year but the number is very dependent on the temperature.
Adults usually live several months.
The merchant grain beetle cannot attack sound kernels. Its flat body form permits access through very small cracks and into imperfectly sealed packages. Adults can fly and they are attracted to light. It is not commonly found in grains, but appears to prefer oilseed products, including nuts and cereal products. It most commonly attacks cereals including rolled oats, rice flour, cake mixes, macaroni, and cookies.