If it has eight legs, that makes your creature a spider not an insect. (Or a lobster or crab, but I am assuming you are not speaking of shellfish.)
Beyond that, more detail is needed regarding:
* size of spider (measurement and proportion of body, legs) * location (country/state, and specify basement, flower garden, etc) * behavior (movement, feeding, speed) * web (if any) * markings
Ants Earwigs have the pinchers or "cerci" at the back end.
You need to be much more precise. Insects have 6 legs. Spiders and other arachnids have 8 legs. Millipedes and centipedes have many more.
It sounds like the description of an assassin bug. Assassin bugs have a distinct orange head with pinchers for mouthparts, a striped body, and six legs. These bugs are beneficial predators that feed on other insects.
All insects have six legs. There are many many tiny ones. You need to be more specific.
Pinchers in the back sounds like an earwig.
A brown bug with long antennae and six legs typically possesses the characteristics of being an insect.
The name of the flat brown bug with 6 legs commonly found in households is a cockroach.
the lobster-like insect is called a 'pseudoscorpion'
The characteristics that distinguish a brown bug with long antennae and 6 legs from other insects are its specific color (brown), long antennae, and the number of legs (6). These features help to identify and differentiate this bug from other insects.
All members of the arachnid family have eight legs each. This includes:SpidersScorpionsTicksMites
Sounds like a house centipede.
An ant (insect) fits that description.