biostudies-literatureFabian STIsaac Newton TrustImperial College LondonWellcome TrustUniversity of CambridgeBiotechnology and Biological Sciences Research CouncilAir Force Office of Scientific Researchjeb243568https://www.ebi.ac.uk/biostudies/studies/S-EPMC8920034biostudies-literatureUnknown225(4)The miniature robber fly Holcocephala fusca intercepts its targets with behaviour that is approximated by the proportional navigation guidance law. During predatory trials, we challenged the interception of H. fusca performance by placing a large object in its potential flight path. In response, H. fusca deviated from the path predicted by pure proportional navigation, but in many cases still eventually contacted the target. We show that such flight deviations can be explained as the output of two competing navigational systems: pure-proportional navigation and a simple obstacle avoidance algorithm. Obstacle avoidance by H. fusca is here described by a simple feedback loop that uses the visual expansion of the approaching obstacle to mediate the magnitude of the turning-away response. We nThe Journal of experimental biologyAvoiding obstacles while intercepting a moving target: a miniature fly's solution.PMC8920034FA9550-15-1-0188BB/L024667/1097814/Z/11/ZFA9550-18-1-0339Sumner MEWardill TJFabian STGonzalez-Bellido PTfalseAvoiding obstacles while intercepting a moving target: a miniature fly's solution.The miniature robber fly Holcocephala fusca intercepts its targets with behaviour that is approximated by the proportional navigation guidance law. During predatory trials, we challenged the interception of H. fusca performance by placing a large object in its potential flight path. In response, H. fusca deviated from the path predicted by pure proportional navigation, but in many cases still eventually contacted the target. We show that such flight deviations can be explained as the output of two competing navigational systems: pure-proportional navigation and a simple obstacle avoidance algorithm. Obstacle avoidance by H. fusca is here described by a simple feedback loop that uses the visual expansion of the approaching obstacle to mediate the magnitude of the turning-away response. We n2022-01-01T00:00:00Z2022 Feb2026-05-10T01:38:01.652Z2025-02-19T01:11:40.778ZS-EPMC89200343516825110.1242/jeb.243568