Larder Beetle
Key Features
Adult Larder Beetles (Dermestes lardarius) are 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.
Biology
Outdoors the life cycle of this insect is regulated by the seasons; indoors it may breed continuously throughout the year. Eggs
are laid in batches of 6-8, with the total per female being about 200. The larvae are dark coloured and covered with dark brown
hairs and is characterised by two curved spines on the last body segment. Like the adult, the larva is densely covered with hairs.
The larvae pass through five moults if male, and six if female, during the 35 to 80 days of their lives. The larvae have a strong
tendency to remain in dark places. Just before the larvae pupate they begin to migrate, and are often encountered by
homeowners at this time. These older larvae often bore into materials such as wood, cork, or insulation looking for a place to
pupate. The pupal period lasts about 15 days. The adults mate soon after emerging and eggs are laid near a food source.
If conditions are ideal, a generation may be completed in 40-50 days.
Distribution
Widespread throughout Europe, larder beetles all require a diet which is high in protein. Occurring naturally in bird's nests, this
group of insects is well adapted to infesting intensive poultry units, and is one of the main pests of such areas.
Significance
Major damage 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. Damage to timber caused
by larder beetle larvae (boring in to pupate) can cause structural damage.
Control
Cleaning, inspection, and elimination of infested food sources are the first steps in controlling this pest. Valuable materials which
are infested can be heat sterilised (54°C for 1/2 hour) or frozen (0° for 3-4 days). Once the cleaning has been undertaken, a light
spray with a residual insecticide to wall/floor junctions and potential harbourage sites.
