This database aims to provide comprehensive information on the scale insects (Coccoidea) of the world, of which there are about about 7,800 species. Scale insects vary dramatically in their appearance from very small organisms (1-2mm) that occur under wax covers (some look like oyster shells), to shiny pearl-like objects (about 5mm), to creatures covered with mealy wax. They spend most or all of their lives feeding on plants and are primarily important as plant pests in greenhouses, backyards, and on fruit trees. Scale insects damage millions of dollars worth of food, ornamental, fiber and greenhouse crops each year. Until ScaleNet, information about the pests was buried in thousands of scientific journals and books, making it difficult for the average person to locate. The Agricultural Research Service developed ScaleNet with colleagues in Israel and Canada. It will allow anyone to locate every scale insect that experts over the centuries have found and named. Through keyword searches and other queries, ScaleNet provides comprehensive information including the insects' biology, classification, naming history, distribution, plant hosts, economic importance, controls and scientific literature about them. Currently, information can be retrieved for 49 families, namely Aclerdidae (grass scales), Albicoccidae, Arnoldidae, Asterolecaniidae (pit scales), Beesoniidae, Burmacoccidae, Callipappidae, Carayonemidae, Cerococcidae (ornate pit scales), Coccidae (soft scales), Coelostomidiidae, Conchaspididae (false armoured scales), Dactylopiidae (cochineal scales), Diaspididae (armoured scale insects), Electrococcidae, Eriococcidae (felt scales), Grimaldiellidae, Grohnidae, Halimococcidae, Hammanococcidae, Inkaidae, Jersicoccidae, Kermesidae (gall-like scales), Kerriidae (lac scales), Kukaspididae, Kuwaniidae, Labiococcidae, Lebanococcidae, Lecanodiaspididae (false pit scales), Lithuanicoccidae, Marchalinidae, Margarodidae (ground pearls), Matsucoccidae (bast scales), Micrococcidae, Monophlebidae, Ortheziidae (ensign scales), Pennygullaniidae, Phenacoleachiidae, Phoenicococcidae (date scales), Pityococcidae, Pseudococcidae (mealybugs), Putoidae, Rhizoecidae, Serafinidae, Steingeliidae, Stictococcidae, Stigmacoccidae, Weitschatidae, and Xylococcidae. The Reference database of ScaleNet includes about 25,000 references, the majority of which have been published since Linnaeus (1758). However, it also contains several pre-Linnean publications that are relevant to the nomenclature and systematics of the Coccoidea. This is a re-implementation of the original version of ScaleNet, a FoxPro application developed by Yair Ben-Dov, Douglass R. Miller and Gary A. P. Gibson with major support from the United States-Israel Binational Agricultural Research and Development Fund. The original application was heavily used by insect scientists and insect identifiers for close to two decades. This version was built by Mayrolin García and Nate Hardy using open source software (Linux, SQLite, Django (a Python web framework), and Apache2). Its development is supported by a Specific Cooperative Research agreement between Gary Miller at the USDA Systematic Entomology Lab and Nate Hardy at Auburn University. As part of the re-implementation, the data model was normalized, and the scientific names and classifications of ecological associates were updated and standardized.