IDENTIFICATION GUIDE
Stored product insects
19 species that infest flour, cereals, spices, nuts and pet food. Identifying the right species is decisive: its cycle sets the treatment timeline, and its behaviour tells you where to look for the source.
Active infestation? Don't wait — a certified technician responds within 4 hours, 24/7.
Why identification changes everything
Cycle sets the timeline
From 25 days to over a year depending on species. It determines when the follow-up visit is scheduled.
Flight indicates range
A non-flying species stays near its focus: the source is in the immediate vicinity.
Packaging guides the audit
Piercing species contaminate new product; the others reveal a sealing defect or a supplier issue.
Moths (pantry moths)
Adults do not feed: the larvae consume the product and spin silk threads. An adult flying erratically near the ceiling almost always signals a source in a nearby bag or pallet.
| Species | Size | Cycle | Infests | Pierces packaging | Flies |
|---|---|---|---|---|---|
| Indian meal moth | 16–20 mm | 25–135 j | Processed cereals, dried fruit, nuts, chocolate, pet kibble | Yes | Yes |
| Mediterranean flour moth | ≈ 24 mm | 28–70 j | Flour and processed grain | Yes | Yes |
| Meal moth | ≈ 25 mm | 35–70 j | Mouldy cereals, damp grain | Yes | Yes |
| Rice moth | 13–24 mm | 45–150 j | Rice, cocoa, dried fruit, nuts | Yes | Yes |
| Angoumois grain moth | 12–17 mm | 35–65 j | Whole grain | Yes | Yes |
- Indian meal moth16–20 mm · Reddish and grey
- By far the most common in Quebec. Its wings are two-toned: pale at the base, coppery at the tip — a pattern that identifies it at a glance. Larvae leave clumps of silk that mat the product together.
- Mediterranean flour moth≈ 24 mm · Grey
- A classic problem in bakeries and flour mills: the silk spun by larvae builds up and can clog sieves, augers and equipment ducts.
- Meal moth≈ 25 mm · Brown
- Mainly attacks already spoiled or damp product. Its presence is therefore an indicator: it points to a forgotten item, a torn bag or an unaddressed water event.
- Rice moth13–24 mm · Tan
- Its larvae build characteristic silk tubes as they feed. Unlike several other moths, it also attacks whole, sound grain.
- Angoumois grain moth12–17 mm · Buff
- Infestation often starts in the field, before harvest: adults lay on growing grain. The problem therefore sometimes arrives with the delivery, not from the warehouse.
Beetles (weevils and relatives)
Both adults and larvae feed on the product. Many are tiny (2 to 4 mm) and go unnoticed until they are seen walking on a shelf or in an open container.
| Species | Size | Cycle | Infests | Pierces packaging | Flies |
|---|---|---|---|---|---|
| Confused flour beetle | 2–3,5 mm | 4–90 j | Flour, broken grain, dry milled foods | Low | No |
| Red flour beetle | 3–4 mm | 49–90 j | Flour, broken grain, dry milled foods | Low | Yes |
| Sawtoothed grain beetle | 2–3 mm | 30–50 j | Flour, cereals, dry milled foods | No | No |
| Merchant grain beetle | ≈ 3 mm | 30–40 j | Flour, nuts, oilseeds | Low | Yes |
| Granary weevil | 3–5 mm | 30–50 j | Whole grain | No | No |
| Rice weevil | 2–3,5 mm | 30 j et + | Whole grain, rice, corn | No | Yes |
| Cigarette beetle | 2–3 mm | 30–90 j | Spices, tobacco, dry milled foods, dried herbs | Yes | Yes |
| Drugstore beetle | 2–3,5 mm | 60–210 j | Virtually any dry product, including spices and medication | Yes | Yes |
| Warehouse beetle | ≈ 3 mm | 32–43 j | Grain, dried meat products, dead insects | Yes | Yes |
| Lesser grain borer | ≈ 3 mm | 30 j et + | Whole grain | Yes | Yes |
- Confused flour beetle2–3,5 mm · Reddish brown
- The most common flour mill insect. It does not fly, which confines it to the area where it developed — a useful clue for tracing the source. It gives off an unpleasant odour that taints flour.
- Red flour beetle3–4 mm · Reddish brown
- Nearly identical to the confused flour beetle, but it flies well — letting it colonize areas far from the original focus and making the source harder to trace.
- Sawtoothed grain beetle2–3 mm · Brown
- Recognizable by the six saw-like teeth on each side of the thorax. It does not pierce packaging, but its larvae slip through minute holes — a single sealing defect is enough to contaminate a new box.
- Merchant grain beetle≈ 3 mm · Brown
- Very easily confused with the sawtoothed grain beetle. Practical difference: this one flies and is drawn to light, making it detectable with a light trap.
- Granary weevil3–5 mm · Dark brown
- Elongated snout typical of weevils. The larva develops inside the grain kernel itself, invisible from outside: a shipment can look sound while being heavily infested.
- Rice weevil2–3,5 mm · Brown
- Like the granary weevil it develops inside the kernel, but it flies — so it can spread from one contaminated pallet across an entire warehouse.
- Cigarette beetle2–3 mm · Light brown
- Rounded body with the head tucked under the thorax, giving it a small ball-like outline. Common in spices and seasoning blends; it can also enter from outdoors.
- Drugstore beetle2–3,5 mm · Brown
- Very close to the cigarette beetle; they are told apart by the fine lengthwise striations on the drugstore beetle's wing covers. Its diet is among the broadest of all stored-product insects.
- Warehouse beetle≈ 3 mm · Variable, mottled
- The larvae's hairs (setae) can cause irritation and are a problematic physical contaminant in food processing. The species also feeds on dead insects, letting it survive in empty premises.
- Lesser grain borer≈ 3 mm · Dark brown to black
- Cylindrical body with the head tucked under the thorax, invisible from above. One of the few insects able to attack perfectly sound whole grain.
Other stored-product insects
A mixed group including species that also feed on animal matter, mould or dead insects — often the sign of a forgotten product or an old water event.
| Species | Size | Cycle | Infests | Pierces packaging | Flies |
|---|---|---|---|---|---|
| Black carpet beetle | 3–5 mm | 177–370 j | Cereal products, pet food, wool, furs | Yes | Yes |
| Spider beetles | 1–5 mm | 12–120 j | Mouldy product, debris, rodent droppings | No | No |
| Cadelle beetle | ≈ 8 mm | 65–135 j | Grain, flour, cereal products | Yes | Yes |
| Yellow mealworm beetle | 12–16 mm | 280–630 j | Mouldy grain, neglected damp product | No | Yes |
- Black carpet beetle3–5 mm · Black
- Very long cycle, up to a year. Larvae shelter in floor cracks, under baseboards and behind equipment — a treatment targeting only the product systematically fails.
- Spider beetles1–5 mm · Variable
- Their look is deceptive: a bulbous body and long legs give them a spider-like appearance, but they have six legs. Found mainly in basements, crawl spaces and low-traffic areas — often associated with rodent activity.
- Cadelle beetle≈ 8 mm · Dark brown to black
- The largest species in the group: the adult reaches 8 mm and the larva up to 18 mm. It can live over a year and gnaws structural wood and cardboard in addition to food products.
- Yellow mealworm beetle12–16 mm · Black
- Its presence almost always indicates an old, damp accumulation: silo bottom, residue under a conveyor, forgotten bag. The cycle can exceed a year and a half.
Our method in food environments
In a restaurant, grocery or warehouse, the goal is not to spray: it's to find the focus and document the intervention for compliance.
- 1
Species identification
It sets the cycle, and therefore the follow-up schedule.
- 2
Locating the focus
Inspection of pallets, high shelving, residue under equipment and the oldest stock.
- 3
Targeted removal
Isolating affected lots rather than mass destruction.
- 4
Monitoring traps
Pheromone traps to objectively measure the decline and detect any return.
- 5
Crack treatment
Targeted application away from food-contact surfaces.
- 6
Documentation
Intervention report and log for your MAPAQ inspections.
Frequently asked questions
How do insects get into sealed food?+
Two ways. Some species, like the Indian meal moth or the cigarette beetle, actively pierce cardboard and thin films. Others, like the sawtoothed grain beetle, pierce nothing but their larvae slip through minute holes or sealing defects. In many cases the infestation was already there on delivery: it comes from the supplier, not your premises.
Do I have to throw out all the food if there's an infestation?+
No, not systematically. We first isolate affected products by finding the source (often a single bag or pallet), then inspect neighbouring products. Uncontaminated goods can be kept if transferred to airtight containers. Discarding at random without finding the source guarantees a return.
Are stored product insects dangerous to health?+
They do not bite and do not transmit disease. The risk is mainly physical contamination of the product and, for the warehouse beetle, irritation caused by larval hairs. In commercial settings the main issue is regulatory: their presence is grounds for MAPAQ non-compliance.
How long does elimination take?+
Generally 4 to 8 weeks, with at least one follow-up visit. The timeline is set by the species' cycle: from 25 days for an Indian meal moth in warm conditions, to over six months for a black carpet beetle. The follow-up targets individuals emerging after the first treatment.
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