An insect trap for multiple species of pest insects, especially flying insects that are an indoor nuisance. The trap contains at least two parallel, planar, transparent faces, each face configured to polarize transmitted light into a single plane. The faces are oriented such that the light polarization planes are at substantially right angles. When the trap is attached substantially flush to a window, phototactic insects against the window perceive the trap faces as transparent and are thus induced to crawl in to the trap. However, light is prevented from passing through both faces, substantially obscuring the view of trapped insects inside to a casual human observer.
