Image Source: Bobby Yates
This interesting beetle has very distinct features that give away it's identification very quickly, hence the common names: the big-headed ground beetle and the pedunculate ground beetle. First of all, its whole body is a solid, shiny black color. It's also a member of the ground beetle family. It seems as though this beetle has a very large head, but perhaps it seems this way because of it’s very small and narrow (peduncle) waist-like area that connects the elytra and the pronotum body parts. In comparison with the rest of its body, its pincher-like jaws (mandibles) look fairly large and ravenous. They range in size from 15-20mm.
The Big-Headed Ground Beetle is actually quite common throughout the whole United States with exception to the Pacific Northwest. They are nocturnal creatures so this is why you may not have ever seen one before. During the night, you could probably find one looking for insects to prey on around outdoor lighting. They like gardens, fields, yards, and open land in general. They hide under rocks, logs, foliage, and in mulch throughout the day.
The beetle’s diet typically consists of other insects throughout its path whether it be in eggs, larvae, or adults stage. These beetles probably don’t have many predators once reaching adulthood, but their eggs could be eaten by other soil-bedding insects very easily. They have been noticed to harden their body and become very still when sensing potential danger, almost as if to “play dead” in certain situations.
Reproduction & Life Cycle
The females lay eggs singly throughout the soil. Once they hatch, they eat other small insects throughout their lives in the soil. Larvae and adults become dormant when winter arrives. During the spring, larvae become adults. During the summer, the adults emerge to mate and disperse.
Though they may look pretty fierce, the Big-Headed Ground Beetle is generally not medically harmful. Can they bite? Yes, there have been many accounts of people being bitten by this species, and yes, they can leave a painful one also. But fortunately, there are no records to our knowledge of anyone needing to seek medical assistance after this type of bite. This is only considering adults who have been bitten. Children should be closely monitored and bite areas should be aided as much as possible. We suggest to just avoid this beetle outside or move it elsewhere carefully. These beetles are considered beneficial and are very rarely found a nuisance.
Scarites subterraneus or also known as a Pedunculate Ground Beetle