Sitophilus oryzae, commonly known as the “rice weevil,” is a common insect pest throughout much of the United States, but they are most problematic within homes located in the southern states. The rice weevil is a pantry pest that infests and contaminates stored grains and seeds within homes, and generally, humans cannot detect their presence within grain kernels. The most well known pantry pest species include Indian meal moths, drugstore beetles and sawtoothed grain beetles. However, according to a recent nationwide survey of pest management professionals, the rice weevil was the seventh most commonly managed pantry pest in the US during 2016.
After adult rice weevils fly into homes and access stored food, females make a hole in grain kernels in order to insert an egg. After eggs hatch, larvae feed on grain for around one month, and they do not become visible until the larvae reach adulthood and consume the entire grain kernel. Some of the most commonly infested foods include dry beans, popcorn, and a variety of edible seeds. Rice weevils are not medically harmful, and they only damage grain kernels, but nobody wants to eat food infested with beetle larvae (grubs), and airborne adults can pose a nuisance within infested homes.
In order to eradicate rice weevil infestations, all compromised stored grains must be discarded, but minimally infested grain can be saved with high heat and freezing. Heating infested kernels to 140 degrees for 15 minutes, or cooling infested kernels to 0 degrees for three days will kill rice weevils in all life stages. All pantry shelves and kitchen cupboards where infested grains were located must be thoroughly sanitized, and food should be stored in well-sealed containers. Insecticides should never be used near foods, and heavy infestations may require fumigation. The reddish-brown adult rice weevils are around ⅛ of an inch in length, and the whitish larvae are more compact and less-wormlike than most species of beetle larvae.
Have you ever found beetles in your pantry?