Diduga flavicostata is a species of moth in the family Erebidae first described by Snellen in 1879.

It is found on Java,[1] as well as in Australia (the Northern Territory), India, Sri Lanka, Myanmar, Malaysia, China (Jiangxi, Taiwan, Fujian, Guangxi, Hainan, Sichuan, Yunnan) and Japan.

Head, collar and tegulae are bright yellowish.

Thorax and forewings are dark greyish, where forewings possess bright yellow costal area irrorated with a few black scales.

There is a marginal, bright yellow band with a pale waved inner edge.