NPIPM:Dermestes lardarius
Authors: Ashley Mueller, Buyung Hadi
Beetles comprise the largest order of insects. Adults have four wings; the outer wings are hardened to protect the hind wings. Although beetles have wings, not all beetle species are able to sustain flight. Adults and larvae have well-developed chewing mouthparts, which can cause economic damage, depending on the species. In urban areas, the pest status of beetles is usually based on larval feeding habits.
Beetle development stages include egg, larva, pupa, and adult. The length of the life cycle depends on the species. Beetles in the larval, pupal and adult stages are capable of overwintering if they are in protected areas. Beetles often lay their eggs on or near a food source for larvae. Proper storage of organic materials and sanitation are the primary methods of beetle management. Additionally, surveying stored foods and organic materials regularly for all stages of beetle life cycle is a good beetle management practice.
Identification
Adult larder beetles (Dermestes lardarius) are approximately 1/4 inch long. They have ovular, black bodies with a tan-colored band with 6 spots just before the thorax. Larvae are 1/2 inch in length, dark brown, and they are covered in rough hairs. Their appearance is very similar to carpet beetle larvae.
Habitat
Adult larder beetles overwinter primarily outdoors, although they are capable of finding their way indoors. The spring and fall months are a common time for larder beetles to enter the home or building. They may enter the structure in search of dead insects, like boxelder bugs, that have died in attics or wall voids.
Adult larder beetles and larvae feed on high-protein materials like pet food and organic fibers such as furs, hair, feathers, and silk. Larder beetles will also feed upon dead insect or rodent remains that have accumulated within walls or attics. Larvae are capable of boring a short distance into wood, books, or insulation for protection as they seek a place to pupate.
Life Cycle and Seasonal History
In the spring, adult larder beetles locate a food source for their larvae, and they lay single eggs directly into the food source. Throughout the summer, females are able to lay more than 100 eggs. Eggs hatch in less than 12 days, and larvae will feed constantly, going through five or six molt stages. When larvae are ready to pupate, they will bore into the food source or anything in the vicinity. Depending on temperature and moisture conditions, the pupal stage lasts three to seven days. A generation may be completed in 40-50 days in ideal conditions.
Human Interaction and Urban Impact
Indoors, larder beetles are considered a nuisance. However, they have the potential to be economically important pests. Although not very common, larvae are capable of causing structural damage by boring repeatedly to pupate. Even though adults are capable of biting, they are generally not harmful to humans or pets.
Outdoors, larder beetles are beneficial. They play an important role in breaking down and recycling dead animal and organic materials.
Prevention and Management Approaches
Maintaining good sanitation practices is essential in the management of larder beetles. Frequent vacuuming and proper storage of furs and feathers is very important. If the source of larder beetles can be determined, discarding or cleaning the source is a way control can be achieved. Sometimes removal of dead insects inside walls is not practical, but vacuuming cracks and crevices where larder beetles are found is recommended.
If serious problems with larder beetles occur, insecticides containing pyrethrins can be used to manage them. Always use precaution and follow the label carefully before using any insecticide. Insecticides have a certain amount of toxicity to mammals; children and pets are especially at risk.
Other Online Resources
For information regarding labels of chemical control options, please visit NPIC MAPL
