The larder beetle
Who is the larder beetle ?
Latin name : Dermestes lardarius
Order : Coleoptera
Family : Dermestidae
Size : 6 to 9 mm
Colour : brown or black with a yellowish band on the elytra
Location : kitchen and storeroom
Period : all year round
What you need to know about the larder beetle
The larder beetle - Dermestes lardariusAs the larder beetle flies (it is a beetle like the ladybird), it can enter houses either to lay eggs in summer or to take shelter in winter. Outdoors, this insect spends the winter sheltered in the cracks of tree bark.
Males and females are almost identical. The larder beetle can be recognised by :
- its oval, relatively flat and hairy body, dark brown or black in colour,
- 2 short club-shaped antennae attached to the head,
- the black spots near the pronotum, the part of the thorax that hides the head,
- the wide band of small yellowish, greyish or whitish hairs that crosses the elytra. This band has 6 black dots in the centre (three per elytron) of varying shape and size,
- its 2 wings, which are hidden under the elytra and enable it to fly,
- its length, which ranges from 6 to 9 mm.
While the adults prefer flowers, the larvae feed on animal corpses. As dried bacon has become scarce, this insect has adapted to other foods such as pet food and congealed fat. But the larder beetle can also feed on feathers, skins, hair, hams, bacon, dried and processed or putrefied meat, cheese and wool. It also attacks museum specimens, dried insects and stuffed birds.
The larder beetle is a scavenger, feeding on insects and dead animals (necrophagous) present in stored grain.
It can also infest protein-rich plant products. Generally speaking, it infests our food reserves. It has a preference for foods containing oil, fat and animal proteins. However, it can go several weeks without eating.
The larder beetle is frequently found in attics, silos, warehouses and homes. It is also considered a major pest in poultry houses. It is a common and growing pest of homes. The larvae are the most greedy and voracious, burrowing into our books, wood, tiles, pipes, materials, etc., thus weakening our homes.
The larder beetle is not dangerous to human health. It does not sting or bite. It does not transmit diseases. However, its hairs can cause allergies and skin irritations that are not serious in some people.
Reproduction and life cycle
The larder beetle is a holometabolous invertebrate. It undergoes a complete metamorphosis: egg, larva, nymph and adult. The larva moults four or five times before becoming an adult.
They mate in spring or early summer. It is often at this time that they enter dwellings, looking for suitable places to reproduce. After eating protein-rich food, the female lays 100 to 200 banana-shaped eggs in groups of 6 to 8. She lays them directly on or near the food for the larvae. The larvae take between 6 and 11 days to hatch. If the larder beetle finds itself in favourable conditions inside buildings (between 15 and 30°C and the right humidity), it goes from egg to adult in around 40 days. The female can produce five or six generations a year.
In around twelve days, the larva emerges from the egg. It then starts to eat and takes on its characteristic appearance: a body of around 13 mm covered in long hairs, a light brown colour and two small curved spines at the end of the abdomen.
The male larva goes through 5 moults before becoming an adult. The female will go through 6 moults. Once mature, the larva transforms into a pupa. During this stage, the larder beetle is immobile and easy prey for its predators. To ensure its safety, it burrows into food or moves to a safe place.
2 weeks after transforming into a nymph, the larder beetle becomes an adult. It lives for more than a year in favourable conditions.
How do you get rid of larder beetles ?
The presence of the larder beetle is often detected by :
- infestation of food packets and tins
- banana-shaped egg clusters
- the presence of larval exuviae (abandoned moults -->empty little hairy worms)
- fragments of adult beetles
Here are our tips for controlling and eliminating this pest :
- Eliminate all potential food sources, especially all dried-up corpses (rodents, flies, insects),
- Vacuum your home to remove the dead skin, hair and fur you shed every day,
- Clean up all traces of grease (cooker, extractor hood),
- Store your pet food under cover and throw away any contaminated products,
- Install fine mesh over ventilation hatches and vents, and seal any cracks,
- Carefully inspect any bouquets of flowers picked up in your garden,
- Clean cupboards thoroughly and apply insecticides. Use the same cleaning method as for food moths :
Method and a little elbow grease !
1 - Take a large bin bag and throw away anything that isn't in a totally airtight box, even products that look impeccable.
2 - Vacuum every nook and cranny of the cupboard or storeroom.
3 - Fill a basin with hot water + washing-up liquid + disinfectant (organic, of course!). Using a brush, scrub the entire cupboard, leaving no nook or cranny untouched.
4 - When everything is completely dry, treat the entire cupboard with our 4J insecticide diluted to 5% (allow 500 ml for 5 m² of surface area treated). If you're treating large areas, use the same insecticide in concentrated form. In this case, you dilute the insecticide with water in a sprayer at a rate of 5% (50 ml of insecticide for 950 ml of water). Ecodoo Insecticide aerosol or Aries flying insecticide can also be used to treat all enclosed spaces (drawers, furniture, etc).
5 - All that's left is to put all your food back in the cupboards, but always in completely airtight boxes.
Go directly to the detailed product sheets for products to combat larder beetles.
*PAE : ready for use