Indian Meal Moth

Plodia interpunctella

Size8–10 mm (wingspan)

Active Season:Active year-round indoors in heated environments. Outdoor populations peak in summer but indoor infestations occur in any season. More noticeable in fall/winter when adults are spotted flying near lights.

The most common pantry pest in Canada. These small moths infest stored food products, with larvae spinning silken webbing throughout contaminated foods. Also known as pantry moths, flour moths, or grain moths.

Anatomy

Anatomical Details

Identification

ColourDistinctive two-toned wings: pale gray or tan on the inner third, copper-bronze or reddish-brown on the outer two-thirds. Larvae are cream or pinkish with brown heads.

Size8–10 mm (wingspan)

Distinguishing Features

Sharp color division between pale inner and copper outer wing portions
Wings fold tent-like over body at rest
Smaller than a penny when wings are folded
Larvae produce silken webbing in infested food
Adults do not feed and are attracted to lights at night
Infested foods develop a characteristic musty or foul odor

Similar Species

Mediterranean flour moth is slightly larger with uniformly gray wings lacking the distinctive two-toned pattern.
Clothes moths are smaller, uniformly golden or buff-colored, and infest fabrics rather than food.

Biology

Lifecycle

Females lay 100-400 eggs directly on or near food sources. Eggs hatch in 2-14 days. Larvae feed for 2-10 weeks depending on temperature, going through 5-7 molts. Pupation occurs in cocoons attached to surfaces or within food. Adults emerge in 4-30 days and live 1-2 weeks. Complete lifecycle takes 4-6 weeks at room temperature. Can produce 5-6 generations per year indoors.

Diet

Larvae feed on a wide variety of stored products: cereals, grains, flour, pasta, rice, dried fruit, nuts, seeds, spices, pet food, birdseed, chocolate, candy, and dried flowers. Can chew through cardboard, paper, and thin plastic packaging. Adults do not feed.

Nesting

Larvae develop entirely within food products, creating silken webbing and leaving behind frass (excrement) and cast skins. Pupation often occurs away from food in cracks, crevices, or behind pantry shelving. Prefer dark, undisturbed storage areas. Thrive in temperatures of 70-95°F (21-35°C).

Signs of Infestation

Small moths flying near lights

Adult moths seen flying around kitchen lights, especially at night. They have a distinctive zig-zag flight pattern and are attracted to light sources.

Silken webbing in food

Fine white or grayish webbing throughout cereals, flour, grains, or other stored foods. The webbing clumps food particles together.

Small caterpillars in pantry

Cream-colored larvae (up to 12mm long) with brown heads crawling on pantry shelves, walls, or ceilings, often near infested food.

Cocoons in corners and crevices

Small white or tan cocoons attached to ceiling corners, shelf edges, or inside packaging. Pupae may be visible inside.

Clumped or damaged food

Food products with clumped material, small holes in packaging, or visible larvae and cast skins mixed throughout.

Musty or foul odor

Heavily infested foods develop a characteristic unpleasant smell from frass and larval secretions.

Where They Nest

Kitchen pantries and cupboards
Cereal boxes, flour containers, and pasta packages
Pet food storage areas and bags
Birdseed storage containers
Dried fruit, nut, and spice containers
Basement or garage food storage shelves

Common Nesting Sites

Nesting Site Details

Distribution in Canada

Found throughout Canada wherever food is stored. Most common in heated homes and buildings year-round. Extremely common in Ontario, Quebec, and British Columbia. Can survive and reproduce continuously in climate-controlled indoor environments.

Regional Prevalence

High

Moderate

Low

Rare/Absent

Active Season

Active year-round indoors in heated environments. Outdoor populations peak in summer but indoor infestations occur in any season. More noticeable in fall/winter when adults are spotted flying near lights.

Prevention

Inspect all food products before bringing them home from the store
Store susceptible foods in airtight glass or heavy plastic containers
Rotate stock - use older products first to avoid long-term storage
Clean pantry shelves regularly to remove spilled grains and crumbs
Freeze bulk grains and flour for 4 days after purchase to kill any eggs
Don't buy damaged or torn food packages
Keep pet food and birdseed in sealed containers separate from human food

Professional Treatment

Successful control requires a multi-step approach. First, locate and dispose of all infested food products - even unopened packages near the source. Thoroughly vacuum all pantry shelves, cracks, and crevices. Wash shelves with hot soapy water. Professional treatment may include pheromone traps to monitor populations and targeted applications in non-food areas. Proper sanitation and storage practices are essential for long-term prevention. Follow-up monitoring ensures complete elimination.

Get General Pest Control Service

Scientific Classification