A scorpion is an eight legged invertebrate belonging to the taxonomic order Scorpiones. They are venomous and are related to spiders, mites, ticks, and harvestmen along with other members of Arachnida. Around 90 species of scorpions are found in the United States. They are most commonly found in Southern Arizona, parts of Texas, and Central Oklahoma. Scorpions are feared for their sting which can be fatal to humans, although most of the time they are merely painful and lead to swelling. They are the oldest Arachnids for which fossils are known.  Most scorpions are nocturnal. They hide under rocks or burrow holes in the ground during the day and come out after sunset.
A scorpion's body is divided into two segments. The cephalothorax and the abdomen. The mesosoma and metasoma make up the abdomen. The cephalothorax makes up the head, claws, and four pairs of walking legs. The frontal half of the abdomen is called the mesosoma. It contains the sexual organs as well as feather-like sensory organs as well as book lungs. The mesosoma is protected by chitinous plates. The tergites protect the upper surface while the sternites protect the lower surface. The metasoma makes up the scorpion's tail. Its tail is divided into six segments. The last segment contains the scorpion's anus, and also bears the telson, the stinger. The telson contains a pair of venom glands. The cuticle makes up the tough armor around the scorpion's body.
Main Physical Features:
- Pectines: the pectines are a pair of "feather-like" sensory organs as mentioned earlier. They are attached to the sternum on the ventral (lower) side of the scorpion. The pectines are most likely important in mating, hunting, and social interaction.
- Pedipalps: the long front appendages that end in the claws. They are used primarily to capture prey. They are also used in the scorpion-mating dance. They are made up of six segments. The size of a scorpion's claws is usually dependent on the species.
- Eyes: most modern scorpions have three sets of eyes. They are located on the top-center of the carapace and on either side of the prosoma. The number of eyes will vary with the species. Scorpion's eyes only pick up areas of strongly contrasting light. Scorpion's eyes are very sensitive though. They are probably not used to capture prey. 
Sting and Venom
All scorpions have venom. Most scorpion venom is meant to be used against other Arthropods or insects, thus it is normally relatively harmless to humans. Scorpions in the family Buthidae have venom that can be harmful and dangerous to humans. One of the most dangerous species is Leiurus quinquestriatus, also known as the deathstalker. This scorpion and others, as well as scorpions in the family Buthidae, have been responsible for many human deaths. Scorpions will usually not become aggressive unless provoked. They will normally run from danger or stay still. 
Scorpions reproduce sexually and all species have individual males and females. Reproduction is done by transferring a spermatophore (a capsule or mass created by males of various invertebrate species, containing spermatozoa) from the male to the female. There is a long courting ritual used to complete this process. After the process is over, the scorpions divide immediately. The male leaves most likely to avoid being eaten by the female although it is not common with scorpions. Scorpions are viviparous (an animal employing vivipary: the embryo develops inside the body of the mother, from which it gains nourishment, as opposed to in an egg). The babies are born one by one. The babies are carried around on the mother's back (as shown to the right) until the young have had at least one moult. The size of a litter depends on the species. The litter can range from three to 100+. The range of a scorpion's lifespan is thought to be approximately 4-25 years.
Scorpions are most abundant and diverse in warmer climates. They have adapted to many climates and habitats such as plains, savannas, deciduous forests, mountainous pine forests, rain forests, and caves. There are many scorpions in the deserts of Africa and the rainforests of South America. They have also been found in elevations of greater than 12,000 feet. Around 90 species of scorpions are found in the United States. They are most commonly found in Southern Arizona and in parts of Texas and Central Oklahoma. Scorpions hibernate during the cold months of the year. 
It is difficult to control scorpions with just pesticides. Some suggestions to keep your home scorpion-free:
- Keep windows in good condition. Make sure they fit tightly to the frame.
- Install weather-stripping along loose windows or doors.
- Make sure to plug any holes or cracks in your home with caulking.
- Keep your home and yard neat and clean. Do not leave trash or boards around the house. 
Arabian fat-tailed scorpion
Unidentified scorpion at the Grand Canyon National Park, Arizona USA.
(Scorpio maurus palmatus)