Ephestia kuehniella Zeller, 1879

Mediterranean flour moth

A pale pantry moth common in flour mills, bakeries, and home kitchens.

Order: Lepidoptera
Family: Pyralidae
Group: Moths
Ontario status: Established, flour mills, bakeries, and home pantries

Why it matters

A premier pest of flour mills, larval webbing mats flour and fouls machinery, causing major economic losses. In homes it ruins flour, cereal and dry mixes.

Origin

Named for the Mediterranean but now worldwide, spread through the global flour trade.

Behavior

Adults rest on walls and ceilings by day and fly at dusk. Larvae stay hidden inside the food, webbing flour into clumps that can clog mill machinery, in homes you'll find webbing inside the flour bag itself.

Living conditions

Flour mills, bakeries, and home kitchens. Larvae live inside flour and grain products, spinning silken tubes as they feed.

Signs of presence

Silken webbing and clumping inside flour bags
Small pale caterpillars (~15 mm) in flour or cereal
Gray moths resting on pantry walls
Musty odor in heavily infested flour

Weaknesses

Adults don't feed and live only 1-2 weeks
Needs dry milled products, sealed containers break the cycle
Silken webbing betrays its presence early
Cold stops development

Myths and facts

Myth It's the same as the pantry moth with bronze wings.
Reality That bronze-tipped one is the Indianmeal moth; this one is uniformly pale gray, different species, similar habits.
Myth Sifting the flour makes it safe.
Reality Webbing, frass and eggs remain behind; infested flour should be discarded.

Research notes

Morphology

Adults 10-14 mm body, wingspan 20-25 mm, noticeably larger than the Indianmeal moth. Forewings pale gray with dark transverse zigzag markings; no bronze coloring. Larvae creamy white, ~15-20 mm at maturity.

Diagnostics

Confirm by size plus gray zigzag forewings without bronze tips. In mills: silken webbing matting flour, larvae in machinery.

Easily confused with

Indianmeal moth, Plodia interpunctella Smaller, with a bronze/copper outer third on the forewing; Mediterranean flour moth is larger and uniformly gray.

Life cycle

Adult: Lives ~1-2 weeks; does not feed.
Egg: Laid on milled products; hatch in ~3-9 days depending on temperature.
Egg to adult: ~8-10 weeks at 25 °C; ~5-6 weeks at 30 °C
Generations per year: 3-5 per year in heated mills; continuous where warm
Nymph or larva: 5-6 instars over 4-8 weeks; spins silken feeding tubes in flour.

Development

Complete metamorphosis: egg → larva (5-6 instars) → pupa → adult.

Reproduction

Females lay 100-300 eggs.

Distribution

Global: Cosmopolitan in milled products
Native range: Mediterranean region (probable)
Ontario: Established, flour mills, bakeries, and home pantries

Ecology

Larvae are flour specialists; silk production mats the food mass and provides pupation shelter. A long-standing model organism for insect development and population ecology.

Resistance

Phosphine resistance reported in some mill populations.

IPM implications

In mills, pheromone traps map adult activity back to breeding foci in machinery, the silk-matting biology means infestations concentrate where flour accumulates undisturbed. Sanitation of dead flour spots matters more than treating open product.

Chemical ecology

Female sex pheromone based on tetradecadienyl acetates, used in monitoring traps; males also produce courtship signals.

Genetics and DNA

No chromosome-level reference genome published as of 2026; draft genome and transcriptome data published in 2022 (Kuenstner et al., Data in Brief).

Taxonomy

Order Lepidoptera, family Pyralidae. Described by Zeller, 1879. A classic laboratory model in genetics and developmental biology.

Open questions

Genetic basis of mill-adapted life-history traits.

References

Hagstrum & Subramanyam 2006, Fundamentals of Stored-Product Entomology
Phillips & Throne 2010, Annu. Rev. Entomol.
Mallis Handbook of Pest Control