What is "spider beetle"

Spider beetles are the approximately 500 species of beetles in the subfamily Ptininae of the family Anobiidae. They are sometimes considered a family in their own right, which is then called Ptinidae. Spider beetles have round bodies with long, slender legs, and lack wings. They are generally 1–5 mm long. Both the larvae and the adults are scavengers. They reproduce at the rate of two to three generations per year.