Drugstore Beetles
Order:
Coleoptera
Family: Anobiidae
Genus:
Stegobium paniceum (L.)
The drugstore beetle is a common
pest of homes and commercial buildings.
Although worldwide in distribution, this species prefers temperate
zones to tropical regions. This
small-sized beetle infests a wide range of foods, especially those consisting
of dried plant or animal material.
Adult beetles and larva may be found in spices, red peppers, flour,
bread, chocolates, stored grains, tobacco, wool, hair, horn, leather,
wood, drugs, textiles, museum specimens, and books – it has been known
to perforate tin foil and sheet lead!
Infestations can be detected by the presence of live beetles or
by round boreholes in damaged goods.
Biology and Identification
Each fertile adult female beetle may deposit up to 75 pearly white eggs under optimal environmental conditions. The larvae go through four to six instars. At maturity, the larvae are about 1/8” (2 to 3 mm) long, C-shaped, and white. They have many short hairs, thoracic and abdominal segments of similar width, and well-developed four-segmented legs. The last larval instar will form a cocoon, providing a protective pupal chamber. Generally, the duration of development from egg through larva decreases with increasing relative humidity and temperatures. Development can require a minimum of 40 days when the temperature is near 86 degrees F (30 degrees C) and humidity fluctuating around 75 percent. The pupal stage can last from 12 to 18 days.
The adults can live up
to 85 days under optimal conditions.
As typical of anobiid beetles, they are cylindrical in shape with
their head and prothorax bent downward, making the head barely or not
visible from above and giving the beetle a strongly humped side-view appearance.
Adults are about 1/10 to 1/8” (2.25 to 3.5 mm) long and reddish
brown to brown in color. The
body is covered with very fine hairs and the wing covers are distinctly
striated with longitudinal grooves.
The three elongated segments of the antenna club provide a distinguishing
characteristic for the identification of the adult drugstore beetle.
Control
Pinpoint the source of the infestation by careful visual inspection of stored products. Lures are available that will attract adults for detection and monitoring purposes.
Destroy infested material if necessary. Treat areas where the goods were stored to prevent re-infestation by residual populations. Standard fumigants will eliminate all life stages and prevent the spread of infestation. But remember, infested foodstuffs may be considered adulterated by the presence of dead insects, and other commodities will still exhibit damage due to larval feeding. Space treatments may provide a temporary control measures until the exact locations of other infestations can be determined. Always review labeling materials prior to any pesticide use.
Researchers are examining
control efforts using heat and cold extremes.
Preliminary results suggest that conditions where the temperatures
of commodities range from 140 degrees to 176 degrees F (60 to 80 degrees
C) for several hours, or conditions where the temperature is below freezing
and held constant for several days with a low relative humidity of 35
percent, are detrimental to all life stages of the drugstore beetle.
(Courtesy of the National Pest Control Association.)