The female chews a hole into a seed or grain kernel and deposits an egg inside, then seals up the opening, leaving the egg behind. When the egg hatches (inside the grain/seed), the larva feeds on the meat inside until it is fully grown. Once fully grown, the adult weevil eats its way out of the grain/seed.

Where do weevils come from?

Weevils usually infest grains and starches like rice, flour, pasta, and cereals. Weevil infestations that start outside may be the result of fruit trees or gardens, which are also food sources. The insects often gather on the sides of homes and move into cracks and gaps that lead inside.

Are weevils already in flour?

If you see flour bugs, they were already there when you bought it. The female weevil lays eggs in the wheat kernel and it can sometimes survive the milling process. The eggs will hatch if they're in warm or humid conditions, or have reached their maturity.