Mastigoproctus giganteus

This species can grow to be 40–60 millimetres (1.6–2.4 in) long, excluding the tail.[2][3] They have six legs used for movement, two long antenniform front legs that they use to feel around for prey and detect vibrations, and two large pedipalps modified into claws that they use to crush their prey.[3] They have a long, thin, whip-like tail, the origin of the common name whipscorpion. From the base of this tail they can spray a substance composed of 85% acetic acid in order to defend themselves.[2] Acetic acid is the main component of vinegar, so the spray smells strongly of vinegar, leading to the common name "vinegarroon".[2][3]

Mastigoproctus giganteus have eight eyes: two in a pair on the front of the head and three on each side of the head.[3] These eyes are very weak, so Mastigoproctus giganteus navigates mostly by feeling with its long front legs, tail, and pedipalps.[3]

It lives in the southern US and in Mexico. Mastigoproctus giganteus preys on various insects, worms, and slugs.[4] It is an efficient predator that feeds on a variety of Arthropods, primarily insects such as cockroaches and crickets, as well as millipedes and other arachnids. It has even been recorded feeding on small frogs and toads. It uses its large pedipalps to hold prey, while the chelicerae tear and bite the prey.[5]

Mastigoproctus giganteus female with egg sac

This species is sold in the exotic animal trade as pets.[6]

• Mastigoproctus giganteus giganteus (Lucas, 1835)
• Mastigoproctus giganteus scabrosus (Pocock, 1902) — Mexico
• Mastigoproctus giganteus mexicanus (Butler, 1872) — Mexico