Abstract: Entomophaga maimaiga Hamber, Shimazu & Soper is not a native entomopathogenic fungus in Europe. In 1999, it was introduced for the first time in Bulgaria. Recent data suggest that E. maimaiga is spreading across Europe. Since 2011 the fungus has been found in several other European countries. First time this fungus was reported in the European part of Turkey in 2011 and in the same year it was also found in Serbia. During the culmination phases (2014) of the latest outbreak of the gypsy moth in the central Serbia, the greatest area (339,989 hectares) was subject to the very high infection rates. The weather plays an important role in the anticipation of the effectiveness of E. maimaiga. April and May 2014 were the favourable months to the germination of the azygospores and to the infection of the gypsy moth larvae which caused the massive epizootics and mortality of gypsy moth larvae (L2-L4 stage). By the microscopic analysis of the dead caterpillars, the presence of the conidiospores and azygospores of the E. maimaiga was confirmed.