Granary Weevil

• It cannot fly: its wings are atrophied and it has entirely lost the ability to disperse on its own, so it travels only with grain moved by people.
• Its remains have been found in Neolithic and ancient Egyptian granaries: it has accompanied agriculture since its beginnings.
• An infested grain looks intact from the outside until the adult emerges, which makes detecting the infestation in time enormously difficult.
• It does not fly: its wing cases are fused and its hindwings reduced. It travels solely with the grain we move.
• The female bores into the grain, lays a single egg inside and seals the hole with a gelatinous plug that hardens at once. The larva and pupa develop entirely inside the grain.
• That is why an infestation goes unnoticed until the adults bore their way out through the husk, by which time the damage is done.
• A single pair can leave up to 6,000 descendants in a year.
• Its continuous respiration creates hot spots in the silo, raising the temperature and adding moisture, which cakes the grain.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Granaries, silos and cereal stores worldwide

Gestation / incubation

The eggs hatch in 8-11 days at 18-20 °C; the full cycle takes 4 to 6 weeks in summer and up to 17-21 weeks in cold conditions

Litter / clutch size

From 150 to 300 eggs, one per grain

Sources consulted: Wikipedia (es): Sitophilus granarius · Bayer Crop Science, ficha Grain weevil · ScienceDirect, Sitophilus granarius · Lucid Keys / EAfrinet, ficha Sitophilus granarius