The immature stages of phytophagous hoverflies and their plant hosts are mostly unknown. This paper describes the larva of Merodon avidus Rossi, 1790 (Diptera: Syrphidae), based on material collected from Đerdap National Park in Serbia. Larvae were found in the bulbs of Ornithogalum L. (Hyacinthaceae) and in the surrounding soil. DNA barcoding was used to identify the species and scanning electron microscopy was used to describe the morphological characteristics of Merodon avidus. Reared material previously identified as Merodon constans (Rossi, 1794) is shown to belong to M. hurkmansi Marcos-García, Vujić & Mengual, 2007.This study was supported by the Ministry of Education, Science and Technological Development, Republic of Serbia, Grant No. 173002 and Grant No. 43002, the Provincial Secretariat for Science and Technological Development, Grant No. 114-457-2173/2011-01 and by the project Status and Trends of European Pollinators, FP7-ENV-2009-1-244090 (STEP)
