In commercial and everyday use, the term weight is usually used to mean mass, and the verb to weigh means to determine the mass of or to have a mass of. Used in this sense, the proper SI unit is the kilogram (kg).
For other uses, see Aphid (disambiguation). Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies, or whiteflies (not to be confused with jumping plant lice or true whiteflies), are small sap-sucking insects, and members of the superfamily Aphidoidea.
Feeding, habitat, distribution, reproduction, anatomy, venom research and more. Facts about the Arizona Bark Scorpion, the Deathstalker Scorpion, the Emperor Scorpion, the Fattail Scorpion. Introduction. Scorpions are creatures that belong to the class of arachnids, the subclass Dromopoda, and the order Scorpiones. In the world, there are between 1,700 and 2,000 species of scorpions organized in 13 taxonomic families.