By Brian Mount, BCE, Urban Product Development Lead
As most pest management professionals (PMPs) know, grain weevils are a persistent and worldwide problem, one that often sends homeowners into a panic. Here are six facts about weevils, and how you can help eliminate them from your customers’ homes:
1. The most destructive stored product pests are of the weevil genus Sitophilus, which includes rice (S. oryza), granary (S. granarius) and maize (S. zeamais) weevils. They infest foods such as grains, flour, cereal and pasta-based products.
2. Stored pest weevils are between 1 and 4mm long. They are brown or copper in color, with chewing mouthparts at the end of their snouts or prolonged heads. Only the rice weevils can fly.
3. Female weevils chew through the husks of grain kernels and deposit one egg. They close each hole with mucus, making the eggs almost undetectable. They can deposit up to 500 eggs during their short lifetime (usually two to five months). Development of the egg depends on the species — anywhere from five days to five weeks.
4. Prevention is the best strategy. Remove old grain, dust, flour and other food particles in and around storage cabinets. Inspect and remove infested food products.
5. Prevent re-infestation by repackaging materials in properly sealed containers. Thoroughly clean and vacuum food storage areas to make sure no insects, eggs or pupae remain. After infested food is removed and the area is completely clean, treat storage areas with a residual insecticide. Aerosols are particularly good for crack-and-crevice application in cabinets.
6. Be thorough. Remember to treat all areas, including wall and cabinet voids, where insects might be hiding. No visible dust should be left on food storage surfaces after treatment. Twenty-four hours after application, vacuum dead insects. Store new products in insect-proof containers and replace in cabinets.