Latin: Oryzaephilus surinamensis
The sawtoothed grain beetle is in Latin named Pryzaephilus surinamensis. The beetle is a grain pest that originates from tropical regions. In Denmark, this species does not live in the wild, as the danish nature does not provide the optimal living conditions for the sawtoothed grain beetle. The conditions in heated rooms are however good and this is where they survive and multiply.
Appearance
Sawtoothed grain beetles are small approximately 3 mm long. They are flattened and dark brown, on the chest they have serrated strips. The wings are fully developed, yet one never sees the saw-toothed grain beetle fly. The larvae are also small, they are only three to four mm long. The head of the larvae is dark, while the rest of the body is yellowish white.
The beetle is often mistaken as the merchant grain beetle, as their appearance is similar.
Biology and behavior
In general, the saw-toothed lifetime is 6-10 month. They can however be up to three years old, but that is not the norm. The females are extremely reproductive, as she lay about 400 eggs during their lifetime. It varies whether the eggs are laid in small groups or individual but the are typically placed in loose grain or similar products.
The optimal conditions for the larvae are temperatures of 32 degrees. At this temperature, the development from egg to larva to fully grown takes 25 days. If the temperature is 20 degrees, the development takes 2 months and if the temperature is below 18 degrees it will not be possible for the sawtoothed grain beetle to reproduce.
Damage
Sawtoothed grain beetles are often found in the company of other grain pests in grain storage. It is not very likely that the saw-toothed grain beetle will gnaw hole in grains that have not already been damage, but they do mainly eat the germ. The saw-toothed grain beetle can be found in all kinds of dried plant products. They prefer grain, bread and flour, but they can also be found in chocolate, almonds, and dried fruit.
In fact, it is the larvae that primarily eat the grain and foods and not the adult saw-toothed grain beetle. However, it is the presence of the beetles that is unwanted.
Prevention and control
The sawtoothed grain beetle feeds on grain products and food in a warm environment. Preventing the pest is best done by storing food stuff as cool as possible in tightly closed containers.
If the household or warehouse is attacked by the beetle anyway, the best control method is to inspect cupboards and shelves thoroughly. All attacked items must be treated or discarded. Items can be treated by storing them for a week in -6 degrees. This will kill the sawtoothed grain beetle in all stages, both eggs, larvae, as well as the adult beetles.
Another method is -18 degrees for 24 hours, which gives the same result. Subsequently, the areas should be thoroughly vacuumed. Cracks and fissures can be sprayed with an insecticide. The insecticide must of course be approved for the purpose.
Even if you have carried out this control thoroughly, you will most likely encounter several the saw-toothed grain beetle in a period. This is because the beetles tend to wander around. They will, however, die out if you simply store this beetles’ favorite items in tightly closed containers in a cool environment.
If you still after those measures encounter the sawtoothed grain beetle in larger numbers, investigate if the beetles are in neighboring apartments, as they can move around through pipe penetrations. Another reason can be that you have bought infested items and unintentionally brought the beetles back again.
If they are found in silos or grain storages, the control is very differently. Here one will use malathion products. Thoroughly cleaning empty silos and storage. Afterwards one can use the malathion powder before the fresh grain is brought in. The saw-toothed grain beetle can also be controlled with diatomaceous based products. If so it is important that both the storage facility as well as grain products is relatively dry.
"Pests in House and Home"
"Bed Bugs - Bites, Stings and Itches"
"Food Pests"
"Husets dyreliv" (Insects Around the House - Only danish)
"Skadedyr i træ" (Timber Pests - Only danish)
"Stuefluen" (Common Housefly - Only danish)