How Are Grain Weevils Exterminated?

How Bad Are Grain Weevils?

Grain weevils or wheat weevils (Sitophilus grainarius) can do considerable damage to grain crops or kitchen pantries. It is the larvae that eat the grain and not the adults. Female grain weevils chew a hole in a single piece of grain and then lay a couple of eggs inside. They then repeat this process for as long as they have eggs to lay. Penn State College of Agricultural Science recommends prevention and pesticides for extermination.

Prevention

Grain weevils are attracted to grains left out in the open. Cleaning up spilled grain and keeping grain in sealed air-tight containers can prevent female grain weevils arriving. Be sure to clean any cracks in the cabinet or floors where grain is stored. If any grain particles get in those cracks, they will also attract weevils. Penn State recommends to farmers to spray any grain storage bins six weeks before adding grain to them.

Pesticides

The usual pesticides for grain weevils are pyrethrins, which acts to paralyse the weevil. Pyrethrins are found in commercial insect sprays for ants and roaches. Be sure to remove and dispose of any grain that is already contaminated. There are also now grain weevil pheromone lure traps available, which mimic the scent of weevils ready to mate, but they only kill some types of grain weevils.

Resources

• PennState: Weevils on Stored Grains
• Weevil Control