While the family Dermestidae contains over 1600 species in 66 genera, there are 192 valid species reported in North America. Although the number of dermestids in the United States is still under debate, Biggs 2022 published a dichotomous key with 45 economically important dermestids, including 10 Dermestes species reported in the United States and Canda.
The larder beetle, scientifically known as Dermestes lardarius, indeed has a notorious reputation for infesting stored food products and other organic materials. Its preference for a wide range of food sources, including dry organic matter and animal remains, makes it a common pest in both residential and commercial settings.
DESCRIPTION
The adult larder beetle is dark brown and approximately 1 cm in length on average. The basal halves of the wings are densely covered with coarse, pale-yellow hairs, revealing six dark spots in the yellow band. The ventral side of the body and legs are covered with dense velvety yellow hairs. The larva is brownish and approximately 1.8 cm in length on average. It is characterized by two curved spines on the last body segment. Like the adult, the larva is densely covered with hairs, but the hairs are longer.
Plant Pest Diagnostic Clinic at Ohio State University, (PPDC) received a single larder beetle from a homeowner in Wayne County in February 2024. Since only one specimen was submitted and there were no additional signs of infestation reported, it is possible this was an accidental introduction of the pest from an outside source.
DON’T CONFUSE WITH SIMILAR COMMON NAMES.
While D. lardarius is commonly known as ‘larder beetle’ or ‘bacon beetle’, some authors use the name ‘larder beetle’ for D. maculatus as well, but D. maculatus is more commonly known as ‘hide beetle’. The common name of D. ater is ‘black larder beetle’ (ESA common names). All three species have been reported in the United States. In this article, the name ‘larder beetle’ is referring to D. lardarius. This is one example of how common names can lead to confusion, highlighting the importance of scientific names! D. lardarius can be easily distinguished from D. maculatus and D. ater by the band of yellowish hairs, which is not present on D. maculatus or D. ater.
BENEFITS OF LARDER BEETLES
One interesting aspect of the larder beetle's behavior is its role in cleaning skeletal remains, which has led to its utilization by museum curators and taxidermists. The larvae of these beetles are voracious feeders and can efficiently consume flesh, hair, and feathers from carcasses, leaving behind clean bones. This natural scavenging ability has made them valuable tools in the preparation and preservation of animal specimens for display and study (Charabidzé et. Al., 2022).
Black larder beetle, D. maculatus, is popular among taxidermists because of their larger body size and higher reproductive rate compared to D. lardarius Read More.
Use of D. maculatus in taxidermy - VIDEO
Entomologists often investigate the presence of D. Lardarius and other Dermestes species to investigate human cadavers in forensic cases Read More.
LIFE CYCLE
Larder beetles overwinter as adults, often in crevices of bark or other sheltered places outside the house. Following emergence in the spring, they use their keen sense of smell to find dead animals or insects to oviposit their eggs, ensuring their survival. Through the summer months, a single female can lay more than 120 eggs on spoiled meat or a carcass; the incubation period is around 12 days under favorable conditions (around 660F). The larvae voraciously eat and will molt up to six times until pupation. When they are ready to pupate, the larvae seek non-food material and tunnel into it. The pupation chamber can be on skins, furs, or any other hard material like wood. The pupal stage lasts about 7 days on average depending on temperature and moisture conditions. Under favorable conditions, a generation can be completed in about 45 days. While both the adults and larvae of the larder beetle can feed on the same food source, adults can feed and survive on nectar and pollen as well (Charabidzé et. Al., 2022)
In Ohio, larder beetles may complete more than two generations a year under favorable conditions (around 66oF). Therefore, it is possible that a few pairs of beetles could create an infestation in an ordinary household fairly quickly. Many taxidermists reported three generations of beetles a year with favorable indoor conditions Taxidermy forum.
DAMAGE
Despite their beneficial role in certain contexts, larder beetles can become a nuisance when they invade homes or businesses, infesting stored food products causing damage.
The beetle larvae can infest many pantry items like flour, seeds, nuts etc. It is common that they can reproduce in attics with dead birds, bats, mice and other vertebrates. The adult beetles are often attracted to and will lay eggs on dead birds, insects, stored ham, bacon, meats, cheeses, tobacco, dried fish, dried museum specimens, and pet foods. The developing larvae of the larder beetle then feed on these substrates.
Last instar larvae of the larder beetle then bore into surrounding wood or other hard substrates like corkboard wood, hard parts of taxidermy specimens and museum specimens to pupate, which can cause structural damage.
MANAGEMENT
Proper sanitation along with other control measures are often necessary to manage infestations and prevent further damage to household items or structures.
In a typical household setting, it is best to physically remove the beetles when found. For this, sanitation is the key. First, identify the source of the infestation. Observation, cleaning, keeping food in sealed containers, and proper elimination of infested food sources are vital in controlling this pest. When eliminating infested food, it is advised to sterilize at 00F for a week or in an oven at 140°F for 30-60 minutes before discarding.
Vacuuming thoroughly including cracks and crevices will eliminate the hiding larvae and adults.
It is always a good idea to periodically check any taxidermy, bone mounts, animal skins, and other decorative materials of animal origin for sign of infestation.
The use of insecticides should be the last resort. Residual insecticides can be applied in heavy infestations. There are insecticides specifically named for larder beetles. General household insecticides containing permethrin can be sprayed in cracks and crevices, but these products only provide residual protection. Before application, make sure those products are for indoor use. When using insecticides, always follow the label instructions.
REFERENCES
Biggs, E.M., Herrmann, A., and Cognato, A.I. 2022. Dichotomous key to adults of economically important dermestids (Coleoptera: Dermestidae) of Canada and the United States. Canadian Journal of Arthropod Identification 46: 165 pp. doi:10.3752/cjai.2022.46 https://cjai.biologicalsurvey.ca/articles/bhc-46/
Charabidzé, D.; Lavieille, V.; Colard, T. 2022. Experimental Evidence of Bone Lesions Due to larder Beetle Dermestes maculatus (Coleoptera: Dermestidae). Biology vol, 11, 1321. https://doi.org/10.3390/biology11091321
Charabidze, D., Colard, T., Vincent, B. et al. 2013. Involvement of larder beetles (Coleoptera: Dermestidae) on human cadavers: a review of 81 forensic cases. Int J Legal Med 128, 1021–1030 (2014). https://doi.org/10.1007/s00414-013-0945-1
ESA common names - https://www.entsoc.org/publications/common-names
Herrmann, Andreas & Háva, Jiri. (2013). A new species of the genus Dermestes Linnaeus, 1758 (Coleoptera: Dermestidae) from South America. Studies and reports of District Museum Prague-East - Taxonomical Series. 9. 375-378. https://www.researchgate.net/publication/256512828_A_new_species_of_the_genus_Dermestes_Linnaeus_1758_Coleoptera_Dermestidae_from_South_America
Holloway, Graham. (2023). A review of Dermestes Linnaeus (Coleoptera: Dermestidae) species on the British list. The Entomologist s monthly magazine. 159. 275-285. 10.31184/M00138908.1594.4210. https://orcid.org/0000-0003-0495-0313
Taxidermy forum in taxidermy.net - https://www.taxidermy.net/threads/409589/