Many neriids are sexually dimorphic, with males having more elongated bodies, heads, antennae, and legs than females.

Neriid adults tend to aggregate on rotting vegetable matter or damaged tree trunks.

For terms see Morphology of Diptera Males of some species engage in spectacular combat for territory or access to females.

The rivals elevate their bodies to an almost vertical posture, and pound each other with the ventral surfaces of their heads, strike each other with their forelegs, or try to place each other in a head-lock.

[16] The expression of male secondary sexual traits is particularly sensitive to the protein content of the larval diet.

[17] Developmental plasticity in response to variation in larval diet quality has diversified among populations of Telostylinus angusticollis along the east coast of Australia.

[18] Research on Derocephalus angusticollis has also shown that a male's larval diet can influence the body size of his offspring.