Latin: Sitophilus oryzae
The Rice weevil belongs to a larger family of beetles called snout beetles. The danish name is due to the special “snout” that they all have. Of course, it is not an actual snout, as known from mammals, but it has a shape on the head that can resembles a long and thin or short and thick snout.
As so many other species of beetles, the rice beetle or weevil, only thrives in a warm environment. Which is why you will not often see them in the danish nature, it is simply too cold. Rice weevils does only pose a danger in Denmark if they have been transported here through trade. Rice weevils are a picky, as they only eat grains, seeds, rice, and certain types of pasta like macaroni.
Appearance
Appearance wise, the rice weevil is like the grain snout beetle. However, the rice weevil is smaller. A rice weevil is in average 2.5 to 3.5 mm long so there is not talk of a very large beetle. It may also look like a corn snout beetle, as the two species, at first glance appears almost identical. A rice weevil has four red spots on the coverts. The hind and front body are more even in size than with other beetle species, which tend to have a larger hind body.
Besides the rice weevil can fly with their actual wings, which the cover wings cover. Here it especially differs from the grain snout beetle, which cannot fly. However, it is difficult to distinguish the rice weevil from the corn snout beetle, as both can fly.
Biology and behavior
Further south, the rice weevil has a negative reputation. If the temperatures are high enough, a whole generation of the rice weevil can occur in just one month, where they multiply quickly and cause a lot of damage. The females can in average get 3-6 months old, during this time they can lay up to 400 eggs. Therefor a colony of rice weevils can grow exponentially fast with the right conditions.
Behavior wise the rice weevil is a lot like the grain snout beetle, its close cousin. It acts a lot like the grain snout beetle when laying eggs. The female rice weevil digs a small hole in a grain, where it lay the egg. Afterwards the hole is covered so that the egg is completely hidden inside the grain. The larva then eats the grain until it is ready to come out of the grain shell.
Damage
The rise weevil only damage is eating the food, which you off cause do not want them to. Both larvae and adult beetles are problematic when found in flour or grains as they multiply rapidly. It is important that you rapidly deal with the situation if you suspect or find signs of rice weevils in your home.
As the beetles lay eggs inside the individual grains, it can be difficult to determine whether you have rice weevil beetles in your goods before the adult beetles emerge from the grains. This fact together with their high fertility makes them difficult to control in private homes and in the industry. However, they are not resistant to cold, which results in fewer outbreaks in the cold winter months in Denmark.
Prevention and control
If you have noticed many rice weevils in your kitchen cabinets, you should check your food. If you see signs that there are rice weevil larvae in a specific bag of rice, or grains bags, you should immediately dispose the infested food. If you only suspect rice weevils or larvae in a certain food, you can kill potential larvae, beetles, and eggs by freezing it for a few days. The freezer must be below -18 degrees for this method to work. If you have discovered rice weevils in a bag of rice or flour, it is important that you take immediately action. Other foods should be packed in air-tight packaging, if they are not already in that way the rice weevils won’t be able to wander off into other food stuff.
"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)