In a world of small things, this is a giant. Huge jaws, powerful legs built for the kind of speed a predators needs to snatch a meal, encased in heavy armor.
This a scarites ground beetle, possibly Scarites subterraneous, the big-headed ground beetle. Did we mention it has a big head, though not that much different from other Scarites beetles. Big-headed beetles are common in the United States, including Florida. They're also found throughout the Caribbean, Mexico, Central America and parts of South America.
A word or two about beetles, a.k.a. the order Coleoptera, generally. They are one of the dominant animal forms on this planet. Forty percent of all known insect species are beetles. They represent a quarter of all known animal species.
So what makes a beetle a beetle? All insects have two pairs of wings, front and back. Beetles have their front pair of wings hardened into wing cases called an elytra. Think of a lady bug with its orange-red shell opening up as it takes off to fly. That shell is the elytra. Some beetles don't fly at all. Some are serious pests; most are benign or even beneficial to us humans, like the aforementioned lady bug, which eats aphids.
Ground beetles are one family, called Carabidae, within Coleoptera. There are some 22,000 ground beetle species worldwide, of which about 2,500 are native to North America. Most are nocturnal, usually dark brown or black in color; brightly colored ground beetles are generally going to be active during the day. And within Carabidae is the genus Scarites, which has about 200 members worldwide and about 10 found in North America.
So what differentiates Scarites ground beetles from their cousins? The most obvious to our eyes is the large, fearsome set of curved jaws, or mandibles. Beetles, like all insects, have three body segments — head, pronotum, or thorax, and abdomen.Scarites beetles have a narrow "waist" that connects the pronotum to the abdomen. The scientific term for this bit of anatomy is the peduncle. The elytra — that hard casing that covers the front wings — are shiny and grooved in Scarites beetles. The pronotum is shaped like a cup, straight where it meets the head, curved at the bottom. The pronotum also has two creases that form a "T."
The big-headed ground beetle and Scarites vicinus, which apparently has no common name, are the two most common members of the genus. The two are similar in appearance, as actually are most Scarites beetles. It takes an expert's eyes to separate the two. They're large as beetles go, between an inch and two inches in length, longer than they are wide and shiny black. They are nocturnal hunters.
They inhabit open fields, forest floors, gardens, agricultural fields, under logs and amid leaf litter — basically they'll hang wherever they can find a good meal. Which includes a variety of caterpillars, ants, aphids and other bugs. They'll also eat some plant material. Like all insects, they go through four life stages — egg, larvae, pupae and adult. Their lifespan in total: about a year.