Elongated small beetles, 2 – 3.5 mm long. The saw-toothed grain beetle, the merchant grain beetle and the rust-red grain beetle are primarily of interest. In addition to these, a large number of less known grain beetles exist, which are rare in Europe, which include Cryptolestes minutus (commonly known as the flat grain beetle or the biscuit beetle), Ahasuerus advena and the species Cathartus quadricollis. The latter acts as a grain storage pest in the southern United States, but is not known to live in Europe. None of the above mentioned grain beetles live in the wild in Northern Europe.
They require fairly high temperatures in order to develop and they are tolerant to humidity levels as low as 10% RH. It is assumed that these beetles are supplied to us with imports from warm countries and they can survive in grain stores with hot pockets and in warm rooms in general. The extermination should not cause problems. Grain beetles can be controlled in the same way as weevils and they are even easier to exterminate with poison in grain stores because the larvae live in the seeds.