The Larder beetle (Dermestes lardarius) is a commercial pest as well as a household pest. Prior to mechanical refrigeration, food was stored in a cool area called a “larder.”
The use of refrigeration and the commercial curing of meats have decreased the economic importance of the Larder beetle. However, Larder beetles are still commonly found in homes, museums, mills, and any place that contains a suitable food source.
HOW DO I KNOW IF I HAVE LARDER BEETLES?
- Most people discover a Larder beetle infestation by seeing the adult beetles or finding larvae in their food source.
- Another clue that you may have had Larder beetles is finding a clean skeleton of a dead animal.
- Seeing a few adult Larder beetles does not necessarily mean there is an infestation, especially if they are found in the spring. The Larder beetles may have wandered inside and are not associated with a food source. However, if you continue to find large numbers of adults or larvae, there is a strong possibility of an infestation.
- As long as a food source remains, larder beetles will continue to be a problem.
WHAT DO LARDER BEETLES LOOK LIKE?
- Adult Larder beetles are dark brown to black, oval, and approximately ¼” - 1/3” in length.
- The front portion of the wing covers feature a band of densely covered coarse, pale yellow hairs with 6 dark spots.
- The undersurface of the body and legs are covered with fine yellow hairs.
- Larder beetle larvae are worm-like and approximately ½” in length.
- The larvae are densely covered with reddish brown hairs.
- Larder beetle larvae have two curved spines on the last body segment that curve backwards.
ARE LARDER BEETLES DANGEROUS?
- No, Larder beetles are not known to bite or sting humans.
- However, they can contaminate stored food products, especially cured meats and cheeses.
CAN MY HOUSE BE DAMAGED BY LARDER BEETLES?
- Yes! When the larvae are full grown, they will search for a safe place for pupation and will bore a hole about ½” into wood and other hard materials for protection. Larder beetle larvae can chew through paper, books, foam insulation, cork, light plastic, and even lead and tin.
- Feeding Larder beetle larvae will bore into any commodity containing meat products, including stored ham, bacon, other meats, cheeses, tobacco, dried fish, and pet foods; rendering it inedible
- Larder beetles can be potentially destructive to preserved animal specimens dried museum specimens
- Larder beetle infestations in wall voids or attics are generally considered a nuisance.
WHY ARE LARDER BEETLES IN MY HOUSE/YARD?
Larder beetles are attracted by dead animals.
Larder beetle infestations are commonly caused when other insects -- such as boxelder bugs, Multi-Colored Asian Lady Beetles, or cluster flies -- seek shelter for the winter in wall voids and attics. When large numbers of these fall invaders die, they attract larder beetles to that area the following year.
Adult larder beetles are attracted to and may breed on a small food source such as a dead mouse or squirrel that became trapped inside and died. Often items hidden by the rodents also provide food for the Larder beetles.
WHAT DO LARDER BEETLES EAT?
- Both adults and larvae eat high-protein food, such as dead insects, rodents, and birds, pet food, animal hides and furs, feathers, dried fish, meats and cheese.
- Larder beetles are a type of carpet beetle, but only eat woolens that have been soiled with blood, fish oils, or other high protein stains.
WHAT IS THE LIFECYCLE OF A LARDER BEETLE?
- Larder beetles overwinter as adults in protected places, including in walls and spaces and gaps they find around the outside of buildings.
- Throughout the summer months, female Larder beetles will lay over 100 eggs in food sources they find for their larvae.
- The eggs take about 2 weeks to hatch.
- Larvae will feed for 40-50 days; molting up to five times if male, six if female, before pupating.
- The pupal stage lasts from 3-7 days depending on temperature and moisture conditions
- The total larder beetle life cycle takes about two months.