The Systematic Entomology Laboratory (SEL), a laboratory of the Plant Sciences Institute (PSI) at the Henry A. Wallace Beltsville Agricultural Research Center (BARC) , belongs to the Agricultural Research Service (ARS), which is the main in-house research arm of the United States Department of Agriculture (USDA).

    The psyllids or jumping plantlice (Hemiptera: Psylloidea) are a group of small plant-feeding insects.  Along with aphids, scale insects, and whiteflies, they belong to the group of insects known as the Sternorrhyncha.  The name “Sternorrhyncha” comes from the Greek sternon meaning chest or breast and rhynchos meaning nose, snout, or muzzle and refers to the ventral location of the mouthparts of these insects.   

    Adult psyllids superficially resemble miniature cicadas but are only 2-5 mm in length.  Although adults  have two pairs of wings with reduced venation,  they are weak fliers.  They do, however, have specially developed legs that allow them to jump and the common name of jumping plantlice is aptly applied.  Psyllid  nymphs are dorso-ventrally flattened,  are less mobile than adults, and are often found congregating.   Nymphs of some psyllid species are covered with white waxy secretions and others are gall formers.  World-wide there are over 3000 described species of psyllids which feed mostly on woody dicotyledonous plants.

    Psyllids can damage their host plants by feeding on the sap or injecting toxic saliva that may cause plant galling, malformations, or necroses.  Both adults and nymphs are plant feeding.  Some species are also capable of transmitting plant diseases.  Two such examples are the pear psylla, Cacopsylla pyricola (Foerster) (=Psylla pyricola), which transmits fireblight in pears in North America and the potato psyllid, Bactericera cockerelli (Sulc) (= Paratrioza cockerelli), which serves as a vector of psyllid yellows in potatoes, tomatoes, eggplants, and peppers in North America and Mexico.  Psyllid feeding can also result in the production of honeydew.  This substance is high in sugars and serves as a substrate for fungi which can subsequently reduce photosynthesis in the plant.

    Identification of psyllids is based primarily on the morphology of the adults.  Structural differences of the head, wing venation, antennal length, and genitalia are some of the characters that are used for comparative purposes.   In the past few years, greater emphasis is being placed on nymphal morphology for species identification.

    The U.S. National Psylloidea collection is maintained by the USDA's Systematic Entomology Laboratory but is part of the Smithsonian's National Museum of Natural History.  This collection is located in Building 005 at the USDA's Henry A. Wallace Beltsville Agricultural Research Center in Beltsville, Maryland. The collection has grown throughout the years by way of the efforts, contributions, and collections of psyllid workers such as J. S. Caldwell, D. L. Crawford, D. Jensen, T. Pergande, C. V. Riley, L. M. Russell, E. A. Swartz, and L. D. Tuthill.  Recent computerized enhancements to the collection now allow one to search the holdings using a series of queries.   This collection includes nearly 1500 species represented by over 46,000 pinned specimens, 5,000 microscope slides, three drawers of psyllids on their hosts, 226 holotypes and 27 lectotypes. Specimens that are mounted on microscope slides are curated in room 003 and pinned specimens and dry material are kept in room 001.  In addition to maintaining one of the world's largest collection of psyllid specimens, the collection also has an extensive literature file that includes numerous reprints and original publications.