Latin: Oryzaephilus Mercator
Merchant grain beetles are mainly a problem in food industry and in warehouses, but they can also be found in private homes. Merchant grain beetles live in various grocery products, such as nuts, dried fruit and other dried and / or oily products.
Appearance
The merchant grain beetle grows to an average of 3 millimeters in length when fully grown. It has a warm, dark brown color all over its body and is very flat. It is longer than it is wide and has, as beetles typically do, six legs. As a larva, the merchant grain beetle larva has a yellowish-white color all over its body and a dark head. The larva becomes about 3 to 4 millimeters long.
The merchant grain beetle is sometimes confused with the sawtoothed grain beetle, as the two species are closely related. However, there are easy ways to tell the difference between the two, for instance by keeping an eye on the behavior of the specific beetle. Merchant grain beetles can fly, as they have well-developed wings, and the sawtoothed grain beetle cannot.
Biology and behavior
Females of the species can lay between 200 and 300 eggs during its lifetime. The eggs are simply laid where the merchant grain beetle, which is typically in the goods they eat. The merchant grain beetle can, however, travel relatively far from food. Since they are reasonably small, they can get around easily from apartment to apartment or from warehouse to warehouse.
Like so many other beetles and insects, the development of the merchant grain beetle can depend very heavily on the environment in which it finds itself. A merchant grain beetle can grow large in a shorter time if there is warmer and higher humidity. The ideal climate for a merchant grain beetle is 37.5 degrees and 70% humidity, and in this climate, it can grow to its final size in under 25 days. At 20 degrees, it can take about 100 days for the beetle to grow, and it cannot multiply at all at temperatures below 18 degrees.
The merchant grain beetle does not live in the Danish nature, as it is too cold most of the year. They can therefore only be found in warehouses and similar indoor climates where there is proper heating. If the merchant grain beetle gets outside of Denmark, they do not survive long.
Damage
As the merchant grain beetle cannot survive in Danish nature, it is a pest in various types of groceries. Although they can travel relatively far, they will always try to stay where it is hot, so they typically stay indoors. Inside, there is also better access to food that the beetles need to survive and reproduce.
While it is obviously not good that merchant grain beetle eats of one’s foods, they do not eat much. You do not lose much[LO1] food by having merchant grain beetle in your food stuff. It is merely the beetles’ presence in the food stuff that makes most people want to get rid of them quickly. If you have received a package of peanuts in which you can see merchant grain beetles, you should immediately discard the package, as the beetles will easily be able to move from one package to another.
Prevention and pest control
In warehouses and in similar industrial situations, one must of course contact professionals, as an infestation of merchant grain beetles can compromise the products. However, it is reasonably possible to treat and prevent merchant grain beetles in private homes.
To prevent both merchant grain beetle and other beetles from trying to eat one’s food, one should make sure that all the foods that the beetles will go for, are properly packaged in air-tight concealers. In addition, you can minimize the risk by keeping the merchant grain beetles favorite foods (nuts, almonds, dried fruit, seeds, and the like) cool. If you live in an apartment and experience that the merchant grain beetles simply cannot be removed, there may be a major infestation in a neighboring apartment. In this case, it is a good idea to contact your neighbors and find out if they have problems with beetles in the kitchen.
"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)