Intermediate and Far Infrared Sensing of Nocturnal Insects. Part I. Evidences for a Far Infrared (FIR) Electromagnetic Theory of Cummunication and Sensing in Moths and Its Relationship to the Limiting Biosphere of the Corn Earworm123 (1965)

A theory of communication and location between individuals of opposite sexes of the corn earworm moth, Heliothis zea (Boddie), is presented. The efficiency of such a system is related to physical factors present in the adult earworm environment. The thoracic temperature of the corn earworm can rise from 1° to 8.8°F above ambient temperature and that of the Sphingidae, Abbot's pine sphinx, Lapara coniferarum (J. E. Smith), 17.8°F above the ambient temperature. Thoracic temperatures depend on frequency and amplitude of wing beat. The calculated far infrared (FIR) output associated with the temperature differential was shown to lie between 9 and 11 μ, an area where there is an infrared transmission window in the water vapor of the air. The earworm and other noctuids fly during periods when the water saturation in grams per cubic meter of water is lowest. This condition increases efficiency of transmission in the IR window. The inverse square law states that “the intensity of radiation emitted from a point source varies as the inverse square of the distance between the source and the receiver”; thus, halving the distance of a detector, e.g., a male earworm, from a point source of energy, e.g., a female earworm, would quadruple the FIR energy received by the male. (These factors of the inverse square law and the FIR water vapor window plus the fact that the earworm radiates in this window, lead to the conclusion that FIR radiation would be an efficient method of location between sexes over great distances.) Data collected over the years and in different areas show that the highest percentage of mating for the earworm occurs when highest efficiency of the FIR window (based on the physical weather environment) was attained. Noctuid activity decreases during moonlight at ⅗ to full moon when high FIR radiation from the moon would be expected to interfere with reception between moths. The earworm antennae were shown to have organs with measurements and configurations of FIR resonators. Configurations useful in the 1–5 μ band and 6 μ band also are present and may be tuned for intermediate infrared (IIR) pickup of emitting molecules of sex releaser or feeding and host plant substances. The male earworm responds to the female earworm by feeling the 8th and 9th abdominal segments with both antennae and labial palpi. Because the response takes place within very close quarters and upon contact, the author considers it to be a response to a releaser (i.e., an identification substance) and not to a long distance attractant. These evidences lead to the conclusion that long-distance communication and location are by FIR radiation and that close-in identification for mating and feeding is by IIR pickup of scent molecules. In all probability a similar means of communication is used by other species of noctuids and sphingids, but the corn earworm is used in this example because the author has collected considerable data on this species.