Joseph Berger, Bugwood.org
Dermestes lardarius L
The larder beetle is a commercial pest as well as a household pest. This is a cosmopolitan species which was historically a pest of cured meats in Europe, the United States, and Canada. The use of refrigeration, the purchase of meats in small quantities, and the lack of home curing of meats, have decreased the economic importance of this insect. However, these beetles are still common in homes, museums, mills, livestock facilities, and any place that contains a suitable food source. Typically, these would include any animal by-product such as dried dog food, furs, hides, and feathers. Also, many pantry items can become infested. Another potential food source are dead insects in attic and wall voids that become trapped when they seek an overwintering site. In the fall insects such as flies, bugs, beetles and wasps, accumulate in attics and similar spaces in the home. Many of the hibernating insects die, attracting larder beetles which lay eggs on dead insects. The larvae of the larder beetle then feed on the dead insects.
The adult larder beetle is dark brown and approximately 1/3 inch in length. The basal halves of the wing covers are densely covered with coarse, pale yellow hairs. Six dark spots are usually in the yellow band. The undersurface of the body and legs are covered with fine yellow hairs.
The larva is brownish and approximately 1/2 inch in length. It is characterized by two curved spines on the last body segment. Like the adult, the larva is densely covered with hairs.
Figure 1. Larder beetle adult
Figure 2. Larder beetle larva
Larder beetles often overwinter in crevices of bark or other sheltered places. In early spring, the beetles are attracted to dead insects and will enter the house to oviposit. Through the summer months, females lay more than 100 eggs; the incubation period is less than 12 days. The larvae, preferring spoiled meat, will feed constantly until the next to last molt. They may molt up to five times if male, and six if female. When ready to pupate, the larvae will tunnel into anything in the immediate vicinity, preferring the food source. The pupal stage lasts from 3-7 days depending on temperature and moisture conditions. If conditions are ideal, a generation may be completed in 40-50 days.
Major injury occurs from larval feeding and the boring of the larvae before pupation. Larder beetles will attack stored ham, bacon, other meats, cheeses, tobacco, dried fish, dried museum specimens, and pet foods, for example. The larvae will bore into any commodity containing meat products; they have also been known to bore into structural timbers. Tests have shown that they can bore into lead with ease and tin with some difficulty. The boring is for the purpose of providing a protected place for pupation, not for feeding.
Cleaning, inspection, and elimination of infested food sources are the first steps in controlling this pest. Valuable materials which are infested can be heat sterilized (140° for 1/2 hour) or frozen (0° for 3-4 days). Place food materials that might attract beetles into tight jars or cans to discourage reinfestation.
Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.
Authored by: Steve Jacobs, Sr. Extension Associate
Reviewed January 2013