The pantry full of little critters!

HOLIDAYS ARE GREAT: But when you come back, do you find pests in your pantry?

How many times have we opened our pantry to find flour, rice, or pasta infested with moths or strange little bugs? This often happens, especially during the summer season. In this article, we’ll explore why it occurs and how to prevent it.

The moths are scientifically known as lepidopterans (Lepidoptera). The term, derived from Greek, means “scale-covered wings.” Lepidopterans are an order of insects comprising about 165,000 species, only a tiny fraction of which are associated with stored food products.

The little bugs, on the other hand, are small creatures from the order Coleoptera and the family Tenebrionidae (Tribolium), which includes 32 described species.

HOW TO FIGHT PANTRY PESTS

It’s essential to know that the risk of infestation in food products is always present—even in the most protected environments—and combating infestations can be a challenging task.

When infestations are severe, walls and surfaces are treated with appropriate products and fumigation with chemical gases.

Experience shows how crucial it is to learn prevention methods to minimize the risk of infestation.

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The moths or bugs that develop in food products are often generically referred to as “meal moths.” These pests are not to be confused with clothing moths, although some overlap exists since certain meal moths can also attack textiles.

Meal moths have a complete metamorphosis cycle, consisting of the following stages: egg > larva (caterpillar) > pupa (chrysalis) > adult. For some species found in flour, this cycle can complete in as little as three weeks, and within a few months, the infestation can become severe.

Below is an overview of the most common moths found in flour: Ephestia kuehniella, Plodia interpunctella, Pyralis farinalis, Sitotroga cerealella, Tribolium castaneum, and Tribolium confusum.

CONTAMINATION

The infestation of food products by these pests can start in the field in the case of Sitotroga cerealella, while for other species, it happens post-harvest. These insects attack stored products and primarily infest during processing and storage phases.

Adult insects, unable to penetrate packaging directly, can lay eggs on small food residues (e.g., flour, seeds, or crumbs) left in storage areas. The larvae that hatch, however, can bore through cardboard and plastic packaging with their mandibles.

Another factor that promotes infestation is that food products, especially those from tropical countries, often remain in storage under optimal temperatures for pests to develop. Long transportation periods and improper disinfestation of transport containers exacerbate the problem. As a result, moth eggs—or even larvae—are often already present in cereals.

Detecting infestations can be challenging because they are typically latent and develop first within the product itself. Adult moths prefer twilight hours for movement, reducing their visibility. Signs of their presence include silky webs produced by larvae, resembling spiderwebs, found on food products or storage surfaces.

Caterpillars and adult moths may also be spotted—caterpillars in the corners of walls or on pallets, and adult moths on ceilings or upper walls. Larvae, upon maturing, tend to leave the product and climb to higher locations to form protective cocoons and pupate.

WHAT DOLCI & PANI DOES TO LIMIT THIS ISSUE

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• Inspect incoming goods: Avoid storing products with damaged or visibly contaminated packaging.
• Thorough cleaning: Clean storage areas and equipment, checking for potential infestation sources like decorative items with grains or dried flowers, nuts, or food residues behind equipment or furniture.
• Periodic treatment of transport vehicles.
• Pheromone traps: For adult moths, pheromone traps are available. These traps emit a specific “scent” (pheromone) that attracts males, trapping them on a sticky surface.
• Shorter storage times: Rotating stock frequently minimizes the development time of pests.
• Controlled storage conditions: Store products in low-humidity, temperature-controlled environments, well below the optimal range for pest reproduction.

Below is a table showing the optimal temperature and development duration for the most common species:

Infestation in food products, such as flours and grains, is an unavoidable issue. The milling industry has made great strides in minimizing the presence of moth eggs in flour through improved processing techniques. However, total elimination is only possible with chemical treatments, which pose risks to human health. Prevention through proper storage methods and maintaining temperatures below the pests' reproduction threshold is the best strategy.

In the following lines we report photos of the most common types of weeds.

EPHESTIA KUEHNIELLA Nome comune: Tignola grigia della farina	PLODIA INTERPUNCTELLA Nome comune: Tignola fasciata
PYRALIS FARINALIS Nome comune: Tignola della farina	SITOTROGA CEREALELLA Nome comune: Vera tignola del grano
TRIBOLIUM CASTANEUM Nome comune: Tribolio delle farine	TRIBOLIUM CONFUSUM  Nome comune: Tribolio

Ribadiamo che il problema delle infestazioni sulle derrate alimentari, e quindi sulle farine o sfarinati, è un problema ineliminabile. Grandi passi ha fatto l'industria molitoria, con opportune tecniche di lavorazione, per abbassare notevolmente la presenza di uova di tignole nelle farine, ma non è ancora possibile, salvo l'utilizzo di trattamenti chimici, peraltro dannosi per la salute umana, la loro completa eliminazione. Meglio quindi prevenire con le opportune modalità di conservazione, al di sotto della temperatura ottimale di riproduzione e sviluppo dei parassiti.