A beetle named for its history of feeding on pharmaceutical drugs sounds like an unlikely bed bug look-alike. Yet at roughly a tenth of an inch long and reddish brown, a drugstore beetle can cause plenty of confusion when someone finds one indoors.
Drugstore beetles and bed bugs are easy to separate once you can see their body shape. Drugstore beetles are small, cylindrical, humpbacked beetles with hardened, grooved wing covers and antennae ending in a three-segmented club. Bed bugs are broadly oval, flattened, wingless blood feeders. Drugstore beetles infest stored products rather than feeding on people.
Where you keep finding the insects can provide another useful clue. A recurring drugstore beetle problem points toward an infested dry product or other suitable material that needs to be located.
Drugstore Beetles Really Are Named After Drugs
The drugstore beetle, Stegobium paniceum, has an unusually broad diet.
Its common name comes from its documented ability to feed on pharmaceutical drugs, but that is only one part of its menu. Drugstore beetles can infest flour, dry mixes, bread, cookies, chocolate, spices and numerous other dried products.
They are not limited to food either. Materials documented as susceptible include wool, hair, leather, books and museum specimens. Larvae cause most of the feeding damage.
That diet immediately separates them from bed bugs. Bed bugs are parasitic insects whose nymphs and adults take blood meals from warm-blooded hosts.
So while both insects may appear brown and small from a distance, they are indoors for completely different reasons.
The Body Shape Is the Fastest Difference
An adult drugstore beetle is approximately one-tenth of an inch long, cylindrical and light brown to reddish brown. Its head bends downward, producing the characteristic humpbacked profile.
Look at a bed bug from above and the difference becomes much clearer. Adult bed bugs average about 5 mm long and have a broadly oval, dorsoventrally flattened body. Their wings are reduced to small pads rather than forming functional wing covers.
The drugstore beetle is a true beetle, so its hardened forewings form wing covers, or elytra, across the back.
Those covers carry another useful identification feature. Penn State describes distinct grooves running along the drugstore beetle’s wing covers.
A bed bug has nothing comparable.
The Antennae Confirm the Identification
The antennae provide one of the clearest close-up features.
A drugstore beetle’s antennae terminate in three enlarged segments. That three-segmented club is a standard identification feature for the species.
It is particularly useful because drugstore beetles are commonly confused with cigarette beetles, another small stored-product pest. Cigarette beetles lack the distinctly striated wing covers of drugstore beetles, providing a second feature for separating the two.
If you can clearly see a humpbacked beetle with longitudinal grooves across its wing covers and a three-segmented antennal club, you are not looking at a bed bug.
Our broader comparison of bugs that look like bed bugs helps when the specimen does not match either insect cleanly.
Drugstore Beetles Can Develop Quickly Inside Infested Products
Female drugstore beetles lay their eggs in food or another suitable substrate, giving the larvae immediate access to something they can eat.
University of Florida reports that females can lay up to 75 eggs. After hatching, the larvae tunnel through the infested material before eventually forming cocoons and pupating.
Under suitable conditions, the complete life cycle can take less than two months. Under less favorable conditions, it can extend to several months because development depends heavily on temperature and food.
That means a package can contain multiple life stages before an adult beetle crawling outside it finally reveals the problem.
Finding the Infested Product Matters More Than Finding the Beetles
Drugstore beetle control centers on locating the material supporting the infestation.
Do not limit the inspection to an open bag of flour. Check spices, cereals, pasta, crackers, baking products, pet food, birdseed, dried fruit and other stored dry goods. Their unusually broad diet means overlooked products can keep an infestation going.
Once an infested item is found, heavily infested material should be discarded. Cabinets and shelves should then be vacuumed thoroughly, especially along cracks and corners where spilled food and insects can accumulate.
Susceptible foods can be moved into tightly sealed glass, metal or heavy plastic containers. University of Minnesota Extension also notes that spraying cupboards does not solve a stored-food infestation if the source remains.
That is completely different from responding to bed bugs. A suspected bed bug infestation calls for inspection around sleeping and resting areas, including mattress seams, box springs, bed frames and nearby cracks.
If you are unsure which problem you have, checking for the physical signs of bed bugs can help separate an actual bed bug infestation from a stray stored-product beetle.
Questions About Drugstore Beetles and Bed Bugs
Can drugstore beetles bite people?
Drugstore beetles are stored-product pests, not blood-feeding parasites. Their larvae feed on suitable food and other organic materials rather than taking blood meals from people.
Can drugstore beetles fly?
Yes. Adult drugstore beetles can fly. Bed bugs cannot fly because they lack functional wings, giving you another behavioral difference if you actually see the insect take flight.
What do drugstore beetle larvae look like?
The larvae are small, whitish grubs rather than miniature versions of the adult beetle. They develop inside or around suitable food and other infested materials before pupating.
Does finding one drugstore beetle in a bedroom mean the bedroom is infested?
No. A single adult does not establish where the breeding source is. Drugstore beetles can fly and their potential food sources extend beyond kitchen staples, so repeated sightings should prompt a search for susceptible stored products and organic materials rather than an assumption based only on the room where one beetle appeared.