Both species are found in 4-5% of ships arriving from abroad to British ports. They can live of the same foods, but the merchant grain beetle is most common in products with high contents of oil and fat, while the saw-toothed grain beetle is most common in cereals. The merchant grain beetle requires slightly higher temperatures than the saw-toothed grain beetle and it is not as cold tolerant.
Normally the saw-toothed grain beetle is found in unheated grain storages. In heated rooms, such as kitchens, the two species are equally frequent. In the Danish grain storages the saw-toothed grain beetle is particularly attached to warm areas that eventually occur around local granary weevil infestations. During the slightly warmer conditions in England, grain which is placed too warm can be strongly affected by saw-toothed grain beetles in a matter of weeks. This phenomenon is not known in countries as for example Denmark.