Each grasshopper only has one labium. The labium is the lower lip which is involved in crushing food into smaller pieces.

The labium is the lower lip of the grasshopper. It has a sharp edge that allows the animal to break up food.

A correct medical synonym for "upper lip" is "labium superius oris". A correct medical synonym for "lower lip" is "labium inferius oris".
The anatomic term for the upper lip is the "labium superius oris" and the lower lip is "lower lip" is "labium inferius oris".

Grasshoppers lay eggs, so technically their Labia/Labium would be the orifice on their underside that the eggs come out of.

Labii is Latin, meaning 'of the lip'. For example "Levator Labii Superioris" is the muscle that lifts the upper lip: Levator = lifter; Labii = of the lip; Superioris= of the upper (genitive to agree with labii). The base form of the word (the nominative) is labium; the plural is labia.