Drugstore Beetle (Stegobium paniceum): Identification, Risks & Control

The Drugstore Beetle (Stegobium paniceum) is one of the most common and versatile stored product pests worldwide. As its name suggests, it is often found in pharmacies and herbal shops, feeding on dried medicines, herbs, and pharmaceuticals. However, its appetite extends far beyond drugs—this beetle is known to infest almost anything organic, from grains and pasta to spices, pet food, and even books.

Closely related to the Cigarette Beetle, the drugstore beetle shares many characteristics but has its own unique habits and risks. Because of its extremely wide diet, infestations can appear in unexpected places, making it one of the hardest pantry pests to predict and control.

This article explores how to identify drugstore beetles, their biology, the risks they pose, and effective methods for households and industries to control them.

Identification

Adults

• Size: 2–4 mm long.

• Color: reddish-brown.

• Shape: cylindrical body, similar to Cigarette Beetles, but with finer antennae.

• Distinguishing feature: faint rows of punctures (dots) on wing covers.

• Behavior: strong fliers, often seen wandering near light sources.

Larvae

• Small, white, C-shaped grubs.

• Hidden inside food or dried materials.

• Cause most of the actual damage.

Eggs

• Tiny, white, difficult to detect.

• Laid directly on food surfaces.

Pupae

• Enclosed in silken cocoons made from food particles and frass.

Biology and Lifecycle

• Egg laying: Females lay 20–100 eggs during their life.

• Eggs: Hatch within 1–2 weeks depending on warmth.

• Larvae: Develop for 4–10 weeks, boring through food materials.

• Pupation: Lasts about 1–3 weeks.

• Adults: Live 2–8 weeks, enough time to disperse and reproduce.

Favorable conditions:

• Optimal temperature: 25–30 °C (77–86 °F).

• High humidity accelerates growth.

• Several generations per year in warm climates, allowing populations to spread quickly.

Ecology and Distribution

The Drugstore Beetle is truly cosmopolitan, found in nearly every part of the world. Its association with herbal and pharmaceutical products makes it notorious in apothecaries and health shops, but it also thrives in:

• Grain storage facilities.

• Supermarkets and retail food stores.

• Libraries and archives, where it damages books and bindings.

• Homes and kitchens, especially in cupboards with neglected food.

Drugstore beetles are often found together with Indian Meal Moths, Flour Beetles, and Rice Weevils in mixed infestations, making control more complicated.

Risks and Damage

The risk posed by drugstore beetles comes from their remarkably broad diet.

• Pharmaceuticals: Known to infest pills, herbal remedies, and dried flowers.

• Food contamination: Infests pasta, rice, flour, spices, dried fruit, chocolate, pet food.

• Non-food damage: Attacks leather, upholstery, books, and museum artifacts.

• Quality loss: Infested goods become riddled with holes and dust.

• Health risks: Consumption of contaminated products can trigger allergies.

• Economic impact: Retail recalls and rejections in export markets.

Because they can feed on such a wide range of products, they are considered even more versatile than Cigarette Beetles.

Signs of Infestation

• Small round exit holes in packaging or food products.

• Fine powder, dust, or frass near containers.

• Adults flying near windows or lights.

• Webbing and cocoons inside dried goods.

• Musty odor in heavily infested packages.

Household Control

• Inspection: Check dried foods, teas, herbal supplements, and spices.

• Disposal: Throw away infested packages completely sealed.

• Vacuuming: Clean cabinets, cracks, and storage areas.

• Freezing: Store suspect items at –18 °C for at least 1 week.

• Heat treatment: Warm to 55–60 °C for a few hours to kill all stages.

• Airtight storage: Use sealed glass or plastic containers.

Infestations often coincide with other pests like Flour Beetles or Indian Meal Moths, so a complete clean-out is essential.

Industrial and Professional Control

For warehouses, shops, and food processing facilities, drugstore beetles are more than a nuisance—they are a financial risk.

Sanitation

• Deep cleaning to remove food residues and dust.

• Seal cracks and crevices where beetles may hide.

Monitoring

• Pheromone traps to capture adults.

• Regular inspection schedules for early detection.

Fumigation

• Phosphine fumigation kills all stages of the beetle.

• Used for bulk storage and shipments.

Modified Atmosphere (MA) Storage

• High CO₂ or low O₂ suffocates larvae and adults.

• Effective for sensitive products like herbs and pharmaceuticals.

Temperature treatments

• Heat treatment above 55 °C or deep-freezing below –10 °C kills infestations.

Integrated Pest Management (IPM)

• Combine sanitation, monitoring, and chemical/non-chemical measures for long-term protection.

Case Study: Infestation in an Herbal Shop

A European herbal medicine shop discovered beetles inside packaged chamomile tea and dried lavender. Customers reported small insects crawling inside sealed bags.

Actions taken:

• Quarantined infested stock.

• Removed all dried herbs from shelves.

• Fumigated the storage area.

• Introduced pheromone monitoring traps.

After three months of strict cleaning and monitoring, the shop eliminated the infestation and regained customer trust.

FAQ

Q: Do drugstore beetles only infest medicine?
A: No, they infest a wide variety of foods and dried materials.

Q: Can they fly?
A: Yes, adults are strong fliers, helping them spread quickly.

Q: Do they bite humans?
A: No, they only feed on stored products.

Q: What is the fastest way to get rid of them at home?
A: Discard infested products, freeze or heat-treat suspect items, and store foods in airtight containers.

Q: What other pests are they confused with?
A: They are often mistaken for Cigarette Beetles, but also appear with Flour Beetles and Indian Meal Moths.

Final Thoughts

The Drugstore Beetle is one of the most adaptable and troublesome pests in the category of stored product insects. Unlike pests such as the Granary Weevil or Lesser Grain Borer, which are mostly tied to grains, the drugstore beetle feeds on a stunning variety of items. From herbal medicines and dried flowers to chocolate, spices, and even books, its versatility makes it especially challenging to control.

For households, the solution is usually straightforward: inspect regularly, discard infested packages, and use airtight containers. For businesses, especially those dealing with herbs, pharmaceuticals, or bulk food storage, the problem is far more serious. Infestations can lead to customer complaints, product recalls, and international shipment rejections.

The good news is that with Integrated Pest Management (IPM)—combining sanitation, monitoring, fumigation, and modern storage techniques—long-term control is possible. The key is early detection. Once these beetles establish a foothold, they spread rapidly and can coexist with other pests such as Flour Beetles, Indian Meal Moths, and Rice Weevils.

At the end of the day, the drugstore beetle reminds us that even the smallest insects can have a massive impact when ignored. Vigilance and proactive measures remain the strongest weapons against this ancient and persistent pest.

Read more in our blog and explore guides on many other enemies. Stay informed.

Disclaimer

This article is for informational purposes only. Pest control laws and approved chemicals vary by country. For best results and legal safety, we strongly recommend contacting a licensed pest control professional in your local area. Always make sure that the pest control technician is properly certified or licensed, depending on your country’s regulations. It’s important to confirm that they only use approved products and apply them exactly as instructed on the product label. In most places in Europe, UK, or USA, following label directions is not just best practice—it’s the law.

Author

Nasos Iliopoulos
MSc Agronomist & Certified Pest Control Expert
Scientific Director, Advance Services (Athens, Greece)
Licensed Pest Control Business – Ministry of Rural Development & Food (GR)

References

• Wikipedia – Drugstore Beetle

• Penn State Extension – Drugstore Beetle