Head capsule transmission of long-wavelength light in the curculionidae.
The head capsule of many weevils contains a region that transmits only far-red and near-infrared light. In the alfalfa weevil, Hypera postica, this extraocular cutoff filter evidently works in conjunction with the compound eyes, enabling the insect to use visual cues in locating or recognizing its host plant.
Meyer
J R
JR