Larder beetles (Dermestes lardarius) are common household pests known for infesting dried animal products. These skin beetles can become a nuisance in residential and commercial settings. Their presence often signals an accessible food source within the structure.
Identifying Larder Beetles
Adult larder beetles measure about 1/4 to 3/8 of an inch (7 to 9 mm). They have an oval shape and are dark brown to black. A distinguishing feature is a broad, pale yellow or beige band across their wing covers, which contains six dark spots arranged in a triangular pattern. The body, including the legs, is covered in fine, yellowish or reddish-brown hairs, giving them a somewhat bristly appearance.
Larder beetle larvae are often the first sign of an infestation. These worm-like larvae can grow longer than the adults, reaching up to 1/2 inch (12 to 15 mm). They are reddish-brown to dark brown and covered in dense hairs. A characteristic of the larvae is the presence of two curved, spine-like appendages at their tail end, which curve backwards.
Common Habitats and Diet
Larder beetles are scavengers that play a role in the decomposition of organic matter in natural environments. Outdoors, they are found in protected areas, feeding on dead animals, bird nests, and even bee or wasp nests. They can enter homes in the spring through small gaps and cracks in building exteriors, seeking shelter and food sources. They are also inadvertently brought inside through contaminated food products or packaging.
Once indoors, larder beetles are attracted to high-protein food sources. Their diet includes cured meats, dried fish, cheese, and high-protein pet food. They also consume dead insects, animal hides, furs, feathers, and leather. The beetles are drawn to hidden food sources, such as dead rodents or birds within wall voids, attics, or crawl spaces, which can sustain a large population.
Potential Issues Caused by Larder Beetles
Larder beetles are considered nuisance pests rather than a direct health threat to humans, as they do not spread diseases or bite. However, their presence can lead to several problems. An issue is the contamination of food products; both adults and larvae can infest stored items, rendering them inedible. They can chew through plastic, cardboard, and paper packaging to access food.
Beyond food contamination, larder beetles can damage various non-food items. They infest and destroy preserved animal specimens, furs, leather goods, and even museum collections. When larvae are ready to pupate, they bore into surrounding materials to create protective chambers. This behavior can lead to damage in wood, cork, plaster, insulation, books, and occasionally even soft metals like lead, although significant structural damage is rare. The presence of larvae and their shed skins can also cause general sanitation concerns and, for some individuals, trigger allergic reactions.
Management and Prevention Strategies
Controlling a larder beetle infestation begins with locating and eliminating their food source. This involves a thorough inspection of areas where beetles are most active, including pantries, cabinets, attics, and crawl spaces, to find infested items or hidden animal remains. Any contaminated food products or other infested materials should be promptly disposed of in sealed bags and removed from the home.
After removing the source, cleaning is important. Vacuuming all surfaces, cracks, and crevices helps remove beetles, larvae, and eggs. Emptying the vacuum bag outside prevents re-infestation. Cleaning shelves with a mixture of water and white vinegar can help eliminate food residues and odors that attract beetles. For items like fabrics, washing and drying on high heat can eliminate any remaining beetles, larvae, or eggs.
Preventing future infestations involves several measures. Storing all susceptible food items, including pet food, in airtight glass or plastic containers can deter access. Sealing cracks, gaps, and entry points in the home’s exterior, such as around windows, doors, and foundations, can prevent beetles from entering. Regularly inspecting and cleaning areas prone to pest activity, such as attics and basements, and removing any dead insects or pests, also helps reduce attractants.