Negeviridae is a recently defined taxon of insect-specific viruses (ISVs). Negeviruses have a large geographical distribution and have been isolated from nine mosquito genera (including Aedes and Culex spp.), as well as mining bees, tsetse flies, biting midges, and aphids. They display a unique virion structure that differs from other known ISVs. Research has shown that various negevirus isolates can reduce the replication of several pathogenic arboviruses in vitro, suggesting they may impact the vector competence of several medically significant mosquitoes. Negeviruses have also been shown to efficiently express exogenous proteins via genetic engineering, highlighting their potential in biological control and as protein expression systems. Our research aimed to generate a reverse genetics system and antibody tools to further characterise Castlerea virus (CsV), a novel negevirus from Brisbane, Australia. Hybridoma technology was used to make the first CsV-specific monoclonal antibodies. These antibodies were characterised for their isotype, cross-reactivity to other Australian negeviruses, and their viral protein target, using ELISA, western blotting and immunofluorescent assays. With the newly described antibody tools to detect CsV, circular polymerase extension reaction (CPER) cloning was utilised to produce a robust and flexible reverse genetics system. This system was modified to express zsGreen (a fluorescent reporter) as a direct fusion onto the membrane protein of CsV; a previously defined construct design for another negevirus, Negev virus. Despite the reported stable expression of GFP as a membrane-fusion protein on Negev virus, this construct design with CsV was difficult to recover and zsGreen expression was not stable. However, through the design of new CsV expression strategies, we believe this expression instability can be readily overcome. Our production of a comprehensive toolkit for negevirus detection and genetic manipulation will pave the way for an in-depth exploration of negeviruses as potential biological control agents or next-generation protein expression systems.