They are closely related to the Corethrellidae and Chironomidae; the adults are differentiated through peculiarities in wing venation.

The larvae are aquatic and unique in their feeding method: the antennae of phantom midge larvae are modified into grasping organs slightly resembling the raptorial arms of a mantis, with which they capture prey.

They feed largely on small insects such as mosquito larvae and crustaceans such as Daphnia.

The antennae impale or crush the prey, and then bring it to the larval mouth, or stylet.

The larvae are nearly transparent, sometimes with a slightly yellow cast; their most opaque features are two air bags, one in the thorax, one in the abdomen about in the second last segment.