The grain weevil (length 3 to 5 mm) is part of snout beetle family (Curculionidae), which, with over 45000 described species is most likely the largest family through the animal kingdom. The front part of the head has grown into a sort of trunk in all species, with a little mouth at the very end. On both sides of the trumpet snout you’ll find a club shaped antennas that are bent like an elbow.
Te grain weevil, also known as the granary weevil originally wasn’t part of our fauna, but was introduced to our area long ago with the grain trade. In the Netherlands they exist in grain storages and kitchen supplies. Contrary to its family members, the rice and maize weevil, it can’t fly, but it is great at walking. Its feed consists of grain (mainly wheat and barley) but it also eats products containing starch such as dry dog food, birdseed, peas, macaroni, vermicelli etc.
The female drills a hole in grain or something similar with her snout and lays an egg in it. She then closes up the hole with secretion product that has the same colour as the grain. This way, she can lay two to three eggs per day. The eggs hatches a larvae that eats the grain from the inside. After about four weeks it pupates within the shell of the grain and the adult beetle drills its way out. Because of this, the grain contains less nutrients and it is contaminated with the beetles, larvae and their droppings.
Prevention & Control
The use of pesticides is not necessary in the fight against grain weevils, plus it is very undesirable in the kitchen. Affected supplies must be disposed of and the trash bag should be taken out immediately. Cabinets and boards should be properly vacuumed and cleaned. Insects can survive in food residue left behind in seams or cracks for a long period of time. Check the other supplies and store them in properly sealable cans or pots, so that new contamination is no longer possible.