Common Name: Larder Beetle
Scientific Name: Dermestes lardarius Linnaeus
Class/Order/Family: Dermestes lardarius Linnaeus
The common name of larder comes from the fast that this is a major pest of cured meats and other stored provisions. It is found throughout the United States and the world.
Adults about 1/4-3/8″ (7-9 mm) long; elongate oval. Color dark brown to black with basal 1/3 of elytra (wing covers) with a pale yellow transverse band which contains 6-8 small black spots; abdominal undersurface uniformly dark with no pattern, but covered with fine yellowish hairs (setae); legs covered with fine yellowish hairs. Head without a median ocellus. Antenna short, clubbed, fitting in groove below side of pronotum. Elytra with apical margin smooth, lacking a terminal spine. Larvae up to about 3/8-5/8″ (10-15 mm) long. Color dark brown, covered with long brown hairs (setae).
Head in dorsal view lacking 2 tubercles (small projections). Abdominal 9th segment (nest to last) with urogomphi (paired dorsal processes) sharp-pointed, curved backward at apex/tip in side view.
(1) Other similar desmestid beetles lack a pale transverse band at base of elytra (wing covers).
(2) Pleasing fungus beetles (Erotylidae) with different pale markings and body shiny and hairless.
Skin or hide damaged on its inner surface with holes cut by larvae to reach inner surface; hair loosened by hide destruction on inner surface; molt skins dark brown with numerous brown hairs, 2 sharply pointed posteriorly (to rear) curved spines near rear end; fecal pellets long and slender, 1/64 (0.5-3 mm) long by 1/128″ (0.2 mm) wide. To pupate, mature larvae bore into solid materials such as hams and wood. They may bore into wood to a depth of about 1/2″ (13 mm), with hole width about 1/8″ (3-4 mm). The last larval molt skin is used to plug the entrance/exit hole.
Adult females lay their eggs on suitable larval food or in cracks and crevices where such food is stored; number of eggs ranges form 102-800. Eggs hatch in about 12 days. Male larvae molt 5 times and female larvae molt 6 times BUT there may be more molts under adverse conditions. The mature larva wanders to find a suitable place form pupation which lasts 3-15 days. Developmental time (egg to adult) may require only 40-50 days but usually takes 2-3 months or longer; optimal temperature for development is 64-68F/18-20C.
There is usually only 1 generation per year but in some localities there may be as many as 6. The adults may overwinter in bark crevices and enter buildings in the spring and summer. Adults love about 3-5 months.
The adults and larvae feed on all kinds of animal products such as dried fish, ham, bacon, ,meats, cheese, dried pet food, and dried museum specimens including insects, hides, feathers, horn, and hair. Only occasionally do they attack materials of plant origin such as stored tobacco. Most damage is done by larval feeding, but adults also feed and cause damage. The mature larvae wander in search of solid material in which to pupate. They bore into such material to make a pupal chamber and then plug the entrance/exit hole with the last molt skin.
The primary breeding areas are the pantry and where dried pet food is kept. Unusual places may include: wall/ceiling voids where yellow jackets, honey bees, etc. lived or where cluster flies, face flies, etc. overwintered; rodent bait left in attics, crawl spaces, or basements; wasp and hornet nests in attics, under eaves, around windows, etc., bird nests and poultry houses; dead insects and spiders int he attic or elsewhere; catch trays of insect light traps; behind baseboards where hair accumulates; animal trophies or rugs; stored items made of leather and/or fur; dead animals in the chimney flue, etc. In such places, the larvae and adults feed on the available animal material. Adults avoid light when mating and during egg laying.
The key to controlling larder beetles is to find the primary source(s) of infestation and eliminate it/them. Besides the obvious pantry items, dried pet food, and animal trophies and furs, it may be necessary to check for the more unusual food items and places such as listed above. Ask the customer about both current and past problems with flies in the winter, rodents, birds nesting on/in the building, etc. A thorough inspection should be followed by good sanitation practices and pesticide application when required. Refer to the control section under the general treatment of stored product pests and also fabric and paper pests for details.