The teleomorph of the fungus is well adapted to insect dispersal. The fungus has two mating types, and MAT-1 isolates can only produce perithecia when paired with MAT-2 isolates. However, MAT-2 isolates are self-fertile due to uni-directional mating type switching (Harrington and McNew, 1997; Witthuhn et al., 2000). Most field isolates are MAT-2 and self-fertile, producing many fruiting bodies (ascomata) on the surface of the host or in culture, often within one week. Ascomata are dark brown to black and globose, 130-200 ตm diameter with a long, thin neck up to 800 ตm long, through which the ascospores are exuded. The opening at the tip of the neck has 8 to 15 ostiolar hyphae ranging in length from 50 to 90 ตm. Ascospores are small, hyaline and hat-shaped, 4.5-8 ตm long by 2.5-5.5 ตm wide, and accumulate in a sticky matrix at the tip of the ascomatal neck, where they appear as a cream to pink ball or coil.