Spider beetles are small, scavenging insects frequently encountered in homes. Their rounded bodies and long legs often lead them to be mistaken for small spiders. Despite this spider-like appearance, they are beetles, belonging to the family Ptinidae.
Identifying Spider Beetles
Spider beetles typically measure between 1.5 to 5 millimeters in length. Their coloration ranges from reddish-brown to black, and some species may have a glossy or hairy exterior. A distinctive feature is their globular, often humped, abdomen, combined with long, thin legs and antennae that can make them appear spider-like. For instance, the American spider beetle (Mezium americanum) is known for its shiny, dark reddish-brown to black body with cream-colored legs and antennae. The Australian spider beetle (Ptinus tectus) is similarly shaped but often covered with brown and golden hairs.
Their Natural Environment
Spider beetles are scavengers, often found in dark, undisturbed, and damp locations. They feed on a wide variety of organic materials, including stored food products like grains, cereals, dried fruits, and pet food. These beetles are also commonly found in animal nests, particularly those of rodents or birds, located in attics, wall voids, or crawl spaces. They consume decaying organic matter, such as old wood, feathers, dead insects, and animal droppings.
How They Get Inside
Spider beetles often enter homes on contaminated goods. They can be introduced through packaged food products like flour, pet food, or birdseed that are already infested. These beetles also gain access through structural vulnerabilities such as cracks in walls, gaps around doors and windows, or vents and pipes. Once inside, they may infest living spaces, storage areas, walls, attics, and floorboard cracks. Their ability to chew through packaging materials like cardboard or cellophane facilitates their spread within a home.
Preventing Their Presence
Preventing spider beetle infestations involves regularly vacuuming floors, especially in food storage areas, and promptly disposing of waste to remove potential food sources. Proper food storage is important; dry goods, cereals, and pet food should be kept in airtight containers to prevent access. Sealing cracks, crevices, and other entry points in the home’s exterior blocks their access. Inspecting incoming groceries and secondhand items before bringing them inside helps avoid introducing these pests. Addressing moisture issues, particularly in damp basements or crawl spaces, also makes an environment less appealing.