The Female Ladybug is one of the 24 Golden Bugs in Twilight Princess. Its male counterpart is the Male Ladybug. This bug can be traded to Agitha for a Rupee prize.
Collecting for Agitha
The Female Ladybug is located around the part of Hyrule Field to the south of Castle Town. Cross the bridge at the south gate and turn to the left (Wii) or right (HD). Walk down the steps and near the plants the ladybug will be flying around.
The Male Ladybug is also located around here.