Abstract The association of Harmonia axyridis (Coleoptera: Coccinellidae) infected by Hesperomyces virescens has received attention because this fungus is believed to have a potential effect on the population dynamics of these beetles but we know little about their relationship. Our experiment was designed to study the transmission pattern of H. virescens on H. axyridis over four month. The location and number of fungal thalli, the length of the right elytron, the sex and mating status of females were examined. Although infection rates were similar between females and males, the average number of thalli was always much higher on males than on females (p=0.008) during these four months. More fungal thalli occur on the dorsal side of female hosts, while more fungal thalli are located on the ventral side of males. We believe transmission occurs during mating according to the difference in distribution pattern of fungi (p<0.0001), but it may not the only way. In addition, we found the elytron length of infected females was significant longer than uninfected beetles (p=0.0001) and the difference became significantly in July (p=0.0001).