The collective motion of groups of animals emerges from the net effect of the interactions between

individual members of the group. In many cases, such as birds, fish, or ungulates, these interactions

are mediated by sensory stimuli that predominantly arise from nearby neighbors. But not all stimuli

in animal groups are short range. We consider mating swarms of midges, which interact

primarily via long-range acoustic stimuli. We exploit the similarity in form between the decay of

acoustic and gravitational sources to build a model for swarm behavior. By accounting for the

adaptive nature of the midges’ acoustic sensing, we show that our “adaptive gravity” model makes

mean-field predictions that agree well with experimental observations of laboratory swarms. Our

results highlight the role of sensory mechanisms and interaction range in collective animal behavior.

The adaptive interactions that we present here open a new class of equations of motion, which may

appear in other biological contexts.