Spider Beetle

Description of spider beetles

There are several species of spider beetles in the U.S. that infest stored products. While spider beetles are common and widespread, they are not as abundant nor well known as other household pests.

Spider beetles are generally two to five mm long, oval or cylindrical, long-legged and brown in color. Some species have a superficial resemblance to spiders and this is the source of the common name.

Life cycle of spider beetle

Spider beetles are scavengers both in the adult and in the white, fleshy, grub-like larval stage. Items that have been found to be infested by spider beetles in warehouses, grain mills, museums, and homes include broken grain or grain products, seeds, dried fruits or meats, wool, hair, feathers, rat and mouse droppings, insect and other animal remains, plant and animal museum specimens, books, dried mushrooms, animal feeds and sugar.

Management of spider beetle

Control of spider beetles in the home is similar to other stored product pests. Infested items should be located and eliminated. This may be a challenge because of the large number of possibly infested items. Cupboards or shelves holding infested items should be emptied and then thoroughly vacuum-cleaned. Insecticide sprays are not recommended for controlling insects in stored food cupboards. Washing shelves with detergent, bleach, ammonia or disinfectants will not have any effect on insect pests. As a precaution against reinfestation, you may want to store susceptible foods in sealable glass, metal or heavy plastic containers or in the refrigerator or freezer until you are convinced the infestation is gone. A light spray of household insecticide can be applied to cracks and corners of infested storage areas and may help eliminate any beetles that remain after the thorough cleaning. Spraying alone, that is, without locating and eliminating the infested items, will provide short term relief, at best.