Drugstore beetles come from a large beetle complex of families called the Bostrichoidea that are all very difficult to identify, even to the trained eye. Adults are little reddish-brown beetles about 1/8 inch long. The head is almost totally concealed from view when looking down at the beetle’s back. When viewing from the side, you can see that the head is tucked underneath the prothorax (the segment behind the head) giving it a hunch-backed appearance. The over-all body shape is oval. The head, prothorax and elytra (wing covers) of drugstore beetles are covered in tiny, fine hairs, which are arranged in rows on the wing covers. The larvae are c-shaped, creamy white grubs with a dark head capsule.
The length and timing of the lifecycle for drugstore beetles is dependent on food and temperature. The complete lifecycle can range from two to seven months long. After mating, females lay up to 75 eggs. The newly hatched larvae feed for two to twenty months, depending on the environmental conditions. Pupation lasts for two to three weeks. Adults can live quite long, up to 65 days.
Drugstore beetles commonly feed on dried, stored products like: flour, dry mixes, chocolate, spices, dried herbs, cookies, stored grains and dried fruits and vegetables. Other edible items that this beetle has been found feeding on include: wool, leather, horns, hides, books, and wood. More amazing food items include drugs, toxins, such as strychnine powder, and tin cans! Much like wood-eating organisms, drugstore beetles contain symbiotic yeast that helps them digest these ‘food’ items. This yeast can produce complex nutrients such as B vitamins that make it possible for this beetle to eat junk.
Because they can survive with such interesting diets, an infestation can be difficult to get rid of if these beetles go unchecked for some time. Watch for accumulation of beetles at windowsills. Most samples coming into the office are from curious customers who collected adult beetles from windowsills in autumn. Look for adult beetles in stored food products regularly. Monitoring for the grubs is difficult due to their small size and secretive habits. The most common discovery of drugstore beetles in the grub stage is following the bad taste from your spoonful of morning cereal. Regularly check boxed cereals, mixes and grains, for small shot holes chewed through the sides. Look for small piles of dust and debris coming from containers and bags.
Pesticides are not generally recommended or needed to remedy a drugstore beetle infestation. If the infestation were bad enough to warrant an insecticide, it would be worth calling a A1 Exterminators. Most infestations can be managed by diligence. Careful shopping, cleaning and food storage habits will rid you of your pantry pest problems.