The drugstore beetle
The drugstore beetle, also known as the baker's beetle or grocery beetle, is fond of all our foodstuffs. Its larvae eat everything: vegetable products such as biscuits and other cereal products, herbal products, spices, seeds, oilcakes, chocolate, coffee, etc. and even animal products such as meat, bone and fish meal.
If you have drugstore beetle in your home, you'll need to get rid of them, as they can cause real damage. In this dossier, you'll find a range of answers and natural products to help you combat this gluttonous insect.
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Also known as the pharmacy beetle.Latin name : Stegobium paniceum
Order : Coleoptera
Family : Anobiidae
Adult size : 2 to 3.7 mm long
Larva : 1.5 to 3.5mm long at the end of development
Location : Common in the wild, especially in warm climates and heated buildings
Period : Active from April to September.
Although the drugstore beetle is from the same family as the small or large wood beetle, its feeding method is totally different. Small and large wood beetles are xylophagous insects (from the Greek "who eat wood") while the drugstore beetle is a polyphagous insect ("who eats everything")
What you need to know about the drugstore beetle
A- General information
Insects of the Anobiidae family are unique in their ability to simulate death when they feel in danger. They can thus remain motionless for hours.
The drugstore beetle is a common insect in nature. At the end of winter, it can settle in houses, warehouses or museums and stay there as long as it finds food. Some individuals have been found in Egyptian mummies.
The drugstore beetle can eat practically anything: dry foodstuffs (of plant or animal origin) and non-food items such as books, biological collections or works of art.
But its preference is for starchy products (foodstuffs made from starch, potato starch and their derivatives).
While the adult drugstore beetle avoids light (natural or artificial), it is attracted by ultra-violet rays. This is one way of trapping them.
The adult has a cylindrical, oblong body with a strongly domed thorax that is enlarged at the sides. Its colour can range from yellowish brown, reddish to very dark brown.
The larva resembles a small, whitish arching worm. Its colour darkens slightly as it ages.
B- Development cycle
Like many insects, its cycle depends on climatic conditions (temperature and humidity) and feeding. This cycle can last 2 to 3 months at temperatures between 22° and 25° C, but can last up to 7 months at 17° C. Below 15°C and above 34°C, development is no longer possible. The adult dies at temperatures below -10°C (freezer) and the eggs are killed at temperatures below -5°C.
Under the right conditions, there can be a maximum of four annual generations. The female lays an average of 40 to 60 eggs over a period of around 20 days. These hatch after 1 to 2 weeks.
The larva, because of its very small size and ability to move around, can penetrate tiny spaces and contaminate many foodstuffs. After an average of 8 weeks, the larva builds a cocoon and pupates. This stage lasts between 9 and 18 days, depending on the temperature. As the larva develops relatively slowly, the foodstuffs in question need to be stored long enough for its cycle to be complete. Avoiding long-term storage is also a way of eliminating them.
The drugstore beetle larva has a weakness for all foodstuffs containing starch such as bread (wheat, rice, flour, beans, peas, pasta, pastries), hence its name. If it does not find this type of food, it may very well attack, like anthrene, anything of organic origin: spices, paper, leather, fabrics, dried plants, bamboo, wicker, wool, cork, but also certain old paintings, entomological collections, naturalized animals, skin bindings, archives, parchments, leather, bindings (especially those made of pigskin), etc. It is particularly harmful to old paintings that have been refinished with paste- or flour-based glue. The very small round holes measuring 1 to 1.5 mm that it bores into infested materials before taking flight are a clue to its presence. If necessary, they can even pierce thin sheets of lead as they travel.
As with wood beetles, it is the highly voracious larvae that do the damage. The adults do not feed.
Because drugstore beetles eat a wide variety of foods, the best way to control them depends on where you find them. You'll proceed in the same way as for the food moth if you find it in your packet of pasta, as for the textile moth if you find it in your wardrobe or as for the beetle if you find it devouring your precious books.
As the drugstore beetle has a clear preference for all products containing starch, we'll be looking for it in the kitchen cupboards.
Let's proceed methodically
1 - Empty all your kitchen cupboards.
2 - Throw away any foodstuffs that are infested or not in completely airtight packaging.
If in doubt, you can put your products in the freezer for a few hours if they can withstand it.
3 - Vacuum all the cupboards, paying particular attention to cracks and crevices, and sucking up any debris or crumbs that may be present.
4 - Empty the hoover or throw away the bag. It may contain live larvae.
6 - When everything is completely dry, treat the entire cupboard with our 4J insecticide diluted to 5% (allow 500ml for 5m2 of surface treated). For larger surfaces, you can also use the same product, but in concentrated form. You'll need to dilute it by 5% with water (950ml water + 50ml concentrated insecticide).
7 - In the field of fumigation, Biovétol Habitat fogger completes the treatment against drugstore beetles.. An insecticide based on active ingredients of plant origin (pyrethrum + geraniol), designed for basic treatment of the home. Highly volatile, the solution settles in the smallest nooks and crannies where parasites and insects live. Immediate and long-lasting action.
8 - Put all your food back in the cupboards, but make sure it's in completely airtight tins.
9 - You can put a few food moth repellent sachets in the cupboard. Yes, you read that right : for food moths. This product will have the same effect on drugstore beetle. The smell of bay leaves partially masks the smell of food, preventing them from approaching and eating it.
Source : Insects of Cultural Heritage (Insects dangerous to heritage works): https://insectes-nuisibles.cicrp.fr/en/
For a full study, please consult the "Comparative study of bioactive substances for the protection of heritage assets against insect pests" on the Ceroart website.