How to deal with a larder beetle infestation in the house

Dermestes lardarius, known as the larder beetle here in Canada, is an invasive insect. While it’s not harmful to humans, the larvae and shed skins from moulting can cause allergies in some people. That’s why we consider it important to get rid of larder beetles in your house as soon as you notice signs of their presence.

What do larder beetles look like?

This small beetle belongs to the Dermestidae family. Adults are dark brown or black in colour and measure between 6 and 9 mm in length. Their elongated, flattish bodies have a light brown to yellowish horizontal strip marked by 6 dark spots. Two club-shaped antennae extend from the head, and two pairs of wings are attached to the thorax.

The female lays between 100 and 200 eggs after mating with the male in the spring and early summer. The banana-shaped egg clusters are placed in groups of 6-8 directly on their food source—this might be the corpse of a bird or animal, or oily foods in your pantry. After about 10 days, small larvae appear.

In the larval stage, this insect resembles a small yellowish-brown worm covered with hairs. It measures between 3 and 5 mm and has two curved horn-like appendages, which distinguish it from other Dermestidae (in Quebec, several species can be found). The larva goes through 4 to 5 moults before transforming into a nymph and emerging in its adult form after a rest period.

What do larder beetles eat?

As its name suggests, this beetle commonly feeds on foods that contain animal fats and proteins such as ham, bacon, cooked meats, bones and fat. But that’s not all; they’re gluttons for just about anything:

  • Cheese
  • Cake
  • Dry animal food
  • Rodent and bird carcasses
  • Insects, especially earthworms and ladybugs
  • Flowers
  • Hair and fur
  • Dead skin
  • Fabrics and natural materials

Larder beetles even practice cannibalism and will happily feed on the larvae of other larder beetles.

How they get into your house

The two high-risk times for a larder beetle home invasion are spring and fall. In spring, they’re looking for an ideal place to lay their eggs, while in the fall, they’re drawn in by the warmth of your home.

Their entry points into buildings are usually cracks, torn window screens, attics, wall fissures and other openings leading indoors. They may also be brought into the house on carry-bags, cardboard boxes or previously contaminated foods.

You may notice signs of their presence near food sources. If you find some banana-shaped egg clusters, shed beetle skins or dead larder beetles among your staples and preserves, it’s a pretty good bet that you’ve got an infestation.

You might also find signs behind your stove and in the range hood. They are sometimes found behind electrical outlets and switches and around piping and electrical wires.

Don’t forget to check in your attic. A larder beetle problem can be a sign that there are dead mice or an insect infestation in the seldom-used places in your home.

Larder beetles cause the most damage while they’re in the larval stage. In addition to contaminating food, they can tunnel through wood, mortar and soft metals as they mature into nymphs. The result? A weakened house structure.

How to get rid of this invasive insect

To find out if you’re dealing with a larder beetle infestation, buy some hardware-store sticky traps for insects. If you find more than one beetle in your traps after a week, it’s time to call us—these intruders can overrun your house fast.

In the meantime, here’s what we suggest to prevent an infestation from spreading:

  • Vacuum the floors in all rooms to eliminate food sources and suck up any larvae you come across.
  • Empty your recycling container daily.
  • Dispose of contaminated food in sealed bags and store pet food and staples in airtight containers.
  • Wipe down your stove and range hood to eliminate grease.
  • Install mesh screens on air intake openings in the attic and in your soffits.
  • Make sure that the exterior edges of doors and windows are sealed tight.
  • Repair broken window screens.
  • Seal cracks and openings on the outer walls of the house.
  • Remove any dead insects or pests in the attic, basement or around the house.
  • Make sure there are no wasps or bird nest nests in your ducts.

Although traps are useful for catching adult larder beetles, it takes a spray-on product to deal with nests and larvae. The challenge for the do-it-yourselfer is to know where the nests are. Our pest management experts have the necessary experience to find and destroy them.

Professional extermination services

At all our locations throughout Quebec, our exterminators use products approved by Health Canada to get rid of larder beetles. They will also be happy to advise you on how to prevent a re-infestation.

Better yet, our Régie du Batiment de Quebec license allows us to offer an effective home-sealing service so larder beetles, other pest insects and rodents won’t disturb your peaceful home environment.

Make an appointment with an Elite Pest Control technician today for a free, no-obligation assessment.