The Department of Entomological Sciences at the University of California in Berkeley offers the only diagnostic service in the United States with equipment and experienced personnel for formal laboratory diagnosis of insect diseases. The Diagnostic Service, started in Berkeley by Edward A. Steinhaus in 1944 as an aid to university entomologists, rapidly grew into a worldwide service. The Service was run by Professor Steinhaus and Gordon A. Marsh until 1964, and has been run by the present authors since then (fig. 1).