The drugstore beetle, Stegobium paniceum, is a common pest found globally in homes and commercial storage areas. As a stored product pest, it primarily infests and contaminates dried food items. Its presence can quickly lead to widespread spoilage, making it a significant nuisance for homeowners and businesses. Understanding how to identify this beetle and what attracts it is the initial step toward effective management.
Identifying the Drugstore Beetle
The adult drugstore beetle is small, typically measuring between 2 and 3 millimeters in length. It has a reddish-brown coloration and an oval, cylindrical body shape. While sometimes confused with the similar cigarette beetle, the drugstore beetle has distinct characteristics for proper identification.
Its antennae end in a three-segmented club, differing from the saw-like antennae of its close relative. The hardened forewings, or elytra, feature distinct, fine rows of pits running lengthwise, giving them a striated appearance. The larvae, which cause the primary damage, are small, creamy-white, C-shaped grubs hidden within the infested material.
The Extremely Broad Diet of the Drugstore Beetle
The name “drugstore beetle” originates from its historic tendency to infest dried herbs and pharmaceuticals in apothecaries. This pest consumes an astonishing variety of organic materials, thanks partly to symbiotic yeasts that assist in digesting low-nutrition foods. The larvae are the primary feeders, but adults can also bore through packaging to lay eggs.
Grain-based products are a common target, including flour, cereals, pasta, bread, and crackers. They also readily infest dried pet foods, birdseed, and nuts, often entering a home through a newly purchased package. Beyond starches, they are unique among pantry pests for their ability to thrive on strong spices and herbs, such as paprika, chili powder, and dried ginger.
Their appetite extends to non-food items, complicating control efforts. They feed on leather, wool, books, manuscripts, and dried flowers. The beetles can even chew through packaging materials like tin foil, paper, and light plastics to reach a food source.
Locating the Infestation Source
Finding the original source of the infestation is the most important step in removing drugstore beetles. Infestations often begin with an overlooked item stored for a long time, allowing multiple generations to develop unnoticed. This initial source is typically a forgotten package of pet food in a garage or an expired box of dried goods in a back corner of the pantry.
Telltale signs include small, round “shot holes” in product packaging, created by the adults as they exit. A fine, dust-like material, known as frass, may also be visible near the bottom of containers or on pantry shelves. Adults are good fliers and are attracted to light, so finding them near windows or light fixtures can indicate a nearby infestation.
A thorough inspection must go beyond the main pantry to include areas where non-food items are stored, such as dried flower arrangements or older books. Checking cracks, crevices, and beneath appliances like refrigerators and stoves is necessary, as spilled food particles in these hidden areas can sustain a population. Seldom-used or expired items must be examined closely, as these are the most likely breeding sites.
Effective Elimination and Prevention Strategies
Immediate elimination requires discarding all heavily infested materials, which should be sealed in a plastic bag before being placed in an outdoor trash receptacle. For items with a questionable or light infestation, temperature treatments can kill all life stages. Placing the material in a freezer at 0 degrees Fahrenheit for at least four to seven days is effective.
Alternatively, heat treatment can be employed by placing items in a shallow pan in an oven at 130 to 150 degrees Fahrenheit for at least 30 minutes. Following the removal of infested products, deep cleaning of the storage area is necessary to remove spilled food and any remaining beetles or larvae. Vacuuming shelves, cracks, and corners is recommended before washing surfaces with soap and water.
Long-term prevention focuses on making the pantry inhospitable to the pest. Susceptible dry goods, including flour, cereal, and spices, should be transferred from their original packaging into thick plastic, glass, or metal containers with tight-fitting lids. Purchasing items in smaller quantities ensures a faster turnover of stock, preventing long-term storage where an infestation can take hold. New purchases should be inspected before being brought into the home, and older items should be used before newer ones to maintain stock rotation.