Spider beetles are the approximately 500 species of beetle

Beetle

Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...

s in the subfamily Ptininae of the family Anobiidae

Anobiidae

Anobiidae is a family of beetles. The larvae of a number of species tend to bore into wood, earning them the name "woodworm" or "wood borer". A few species are pests, causing damage to wooden furniture and house structures, notably the death watch beetle, Xestobium rufovillosum, and the common...

. 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 scavenger

Scavenger

Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...

s. They reproduce at the rate of two to three generations per year.

Genera

About 11 genera are recognised :

• Gibbium
  Gibbium
  Gibbium is a genus of beetle present on all continents except Antarctica.-External links:*...
  
  Scopoli, 1777
• Gnostus Westwood, 1855
• Mezium
  American spider beetle
  The American Spider Beetle is a scavenger found in various locations around the world. It is generally seen as a pest that needs to be exterminated as they can be found feasting on a large variety of foodstuffs wherever they are stored. Often mistaken for being part of the order Araneae for its...
  
  Curtis, 1828
• Niptinus Fall, 1905
• Niptus
  Golden spider beetle
  The golden spider beetle, Niptus hololeucus, is a tiny beetle that can be found infesting a wide variety of cereal based food products. It is a temperate species originating in West Asia but now cosmopolitan.The spiderlike body is covered in silky golden hairs and fine scales....
  
  Boieldieu, 1856
• Pitnus Gorham
  Henry Stephen Gorham
  Henry Stephen Gorham was an English entomologist who specialised in Coleoptera.He was a Fellow of the Royal Entomological Society from 1885, a Fellow of the Zoological Society of London from 1881; and a Member of the Societé Entomologique de France from 1887.He wrote very many short scientific...
  
  , 1883
• Pseudeurostus Heyden, 1906
• Ptinus
  Australian spider beetle
  The Australian spider beetle, Ptinus tectus, is a tiny beetle that can be found infesting a wide variety of products. It is among the commonest household pest insects. It is a cosmopolitan species .-External links:** Taxonomy...
  
  Linnaeus, 1766
• Sphaericus Wollaston, 1854
• Tipnus Thomson, 1863
• Trigonogenius Solier, 1849