Insects rarely navigate with a single perfectly informative signal. Self-motion, terrestrial structure, celestial information, wind, airflow, optic flow and other cues differ in availability, persistence and usefulness across habitats and tasks. The central theoretical problem is therefore not simply how insects detect cues, but how navigational systems preserve useful behavior when information is incomplete, conflicting or valid only over limited spatial and temporal ranges. This behavioral framework synthesizes evidence from ants, bees, dung beetles, moths, butterflies and Drosophila while separating behavioral demonstrations, computational sufficiency, neuroanatomical capacity and neural mechanism. It distinguishes four properties that are often conflated: information availability, sensory detectability, behavioral influence and navigational validity. The framework argues that cross-modal integration should be treated as a set of conditional transformations rather than as obligatory cue averaging. Information can be weighted, switched, converted between reference frames, retained in memory or ignored according to task state and environmental conditions. Navigation failure can therefore emerge from discordant cues, inappropriate strategy selection, outdated memory or mismatches between sensory and representational scales. We propose a multiscale architecture in which momentary sensory evidence, journey-scale updating and longer-duration memory remain analytically distinct but interacting. The framework does not assume a universal cue hierarchy, Bayesian integrator or conserved circuit. Its principal prediction is that navigation becomes vulnerable when the validity of information changes faster than sensory weighting, memory or action-selection processes can update.
