Halyomorpha halys is an invasive, polyphagous stink bug from Asia, first reported attacking hazelnut orchards in the Republic of Georgia in 2015. A microsporidian pathogen discovered in Georgian H. halys has been identified as Nosema maddoxi by sequencing the ribosomal small subunit gene. Nosema maddoxi is native to North America and has also been found in China and South Korea; in North America it infects native stink bugs and H. halys. Investigations were carried out during different seasons in three regions of West Georgia in 2018–2019. The highest prevalence of N. maddoxi was detected among overwintered adults collected in May in the Guria region.