Adephaga

The Adephaga is a suborder of beetles. There are more than 40,000 recorded species in ten families. This is the second largest suborder of the order Coleoptera.
The beetles of this suborder include ground beetles, tiger beetles, diving beetles, and whirligig beetles. Most of the species belong to the family of carabids, or ground beetles (Carabidae).
The Adephaga is two groups with a common origin. They are the Hydradephaga (water beetles) and the Geadephaga (ground beetles. They are mostly predatory. The first fossils of both groups are found in the Triassic period. The ground beetles have formidable chemical defences. They have special pygidial glands which squirt out hot, burning chemicals. Bombardier beetles are famous for squirting their nasty chemicals at attackers.