A Novel Interception Strategy in a Miniature Robber Fly with Extreme Visual Acuity

Trevor J. Wardill, Samuel T. Fabian, Ann C. Pettigrew, Doekele G. Stavenga, Karin Nordström, Paloma T. Gonzalez-Bellido

Research output: Contribution to journalArticle

31 Scopus citations


Our visual system allows us to rapidly identify and intercept a moving object. When this object is far away, we base the trajectory on the target's location relative to an external frame of reference [1]. This process forms the basis for the constant bearing angle (CBA) model, a reactive strategy that ensures interception since the bearing angle, formed between the line joining pursuer and target (called the range vector) and an external reference line, is held constant [2–4]. The CBA model may be a fundamental and widespread strategy, as it is also known to explain the interception trajectories of bats and fish [5, 6]. Here, we show that the aerial attack of the tiny robber fly Holcocephala fusca is consistent with the CBA model. In addition, Holcocephala fusca displays a novel proactive strategy, termed “lock-on” phase, embedded with the later part of the flight. We found the object detection threshold for this species to be 0.13°, enabled by an extremely specialized, forward pointing fovea (∼5 ommatidia wide, interommatidial angle Δφ = 0.28°, photoreceptor acceptance angle Δρ = 0.27°). This study furthers our understanding of the accurate performance that a miniature brain can achieve in highly demanding sensorimotor tasks and suggests the presence of equivalent mechanisms for target interception across a wide range of taxa. Video Abstract

Original languageEnglish (US)
Pages (from-to)854-859
Number of pages6
JournalCurrent Biology
Issue number6
StatePublished - Mar 20 2017


  • flight
  • interception strategy
  • invertebrate
  • moving target
  • predation
  • retina
  • spatial resolution
  • tracking
  • vision

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