Fully-grown adults weigh 4 to 7 grams (0.14 to 0.25 oz), with males being slightly larger than females.

The ears are narrow and pointed, with serrated outer edges near the tips, and a long, slightly flattened tragus.

There are two recognised subspecies:[3] Macleay's mustached bats are gregarious and nocturnal, with colonies of several thousand individuals spending the day roosting in deep and humid cave systems.

[4] They leave the caves shortly after sunset, and spend the night feeding on insects, primarily flies and beetles.

[5] Breeding begins in March, and results in the birth of a single young between June and July.