Latin: Sitophilus Granarius
If you have worked with grain or in a grain warehouse, you probably know about the grain weevil. The grain weevil is one of the most well-known pests when it comes to grain stocks, although one can also find grain weevils in the home. Grain weevil can enter your home via grain such as oats, barley, and wheat. However, one can also find them in dog biscuits, bird seeds, pasta, and other grain items.
Grain weevil do not live outdoors in Denmark, so they will prefer to stay close to the food they know they can live on. In the summer, however, they can hike far from their safe areas, as the heat makes it easier for them to get around.
Appearance
The grain weevil is 2.5-5 millimeters long when fully grown. Since the grain weevil is a type of beetle called a snout beetle, its head has the special, thin “snout”. However, this is not as such a nose or snout, but simply the shape of its head. This snout also looks like a horn.
Grain weevil also change color during their lifetime. Like larvae, they are pale and wrinkled, although you rarely see them, as they live inside the center of a grain during the larval stage. Like young beetles, they are reddish brown and slowly become darker brown. As very old beetles, they are completely black.
Biology and behavior
A female grain weevil lays one egg at a time. She gnaws a hole in a grain and lays the egg in it, after which she covers the hole with a secretion. In the center, the egg hatches into a larva, which begins to hollow out the grain, leaving only one shell. It then pupates inside the hollowed-out grain. The adult beetle eats out of the pupa and shell, after which it can now come out and find other beetles and of course more food.
Like so many other beetles, the grain weevil cannot develop unless it is warm enough for it. On the other hand, higher temperatures can lead to the beetle developing faster. It can take 6-12 months for a grain weevil to fully mature at 12 degrees. At 25 degrees, it takes just 1 month for the beetle to fully mature.
Damage
Grain weevil are, of course, a huge risk to grain stocks and similar stocks. If so-called “hot pockets” occur in the grain, grain weevils will be attracted to the area. A hot pocket is an area of the grain that gets wet and hot from outside factors. In bad situations, the hot pocket can reach up to 50 degrees, which will lead to a core in the pocket, which consists of dead grain weevil larvae and fungal hyphae.
In private, you typically only notice a grain weevil attack when you see the small beetles wandering around the kitchen. After this, one can typically easily find the hatching site by finding the food that they mainly flock to. Many people prefer to throw out the infested foods immediately when they detect an infestation from grain weevils.
Prevention and pest control
If you are left with a completely emptied warehouse or an empty silo where you know that there have been grain weevils, the inside must be cleaned very thoroughly. In private, you should store dry food and animal feed cool and with a tight lid, so you avoid both gather and other pests in your food. Also, keep an eye on the foods that you do not use as often as others. To prevent grain weevils, it is best to use a poison gas called phosphorus hydrogen, which should only be used by professionals. Therefore, it is best to call for an exterminator. In private, you should immediately isolate the foods that the grain weevils have been in. You can either heat the affected foods to 55 degrees or put them in a freezer for 24 hours. Grain weevils can wander a away from their favorite place, so clean with a vacuum cleaner in cracks and crevices close to the place, and of course make sure that your food is stored in containers with a tight lids in the future.
"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)