Photographs of wasps or hornets, taken with different temperature sensitive infrared cameras, reveal body temperatures that are sometimes significantly lower than the ambient temperature. This suggests that the hornets possess an intrinsic biological heat pump mechanism which can be used to achieve such cooling. Evidence is presented to substantiate this novel suggestion and to argue that the heat pump is most likely implemented by exploiting a thermoelectric effect in the hornet cuticle. Such a natural heat pump can conceivably also serve to cool the active hornet, engaged in daytime activities outside the nest at ambient temperatures exceeding 40 degrees C, to a body temperature that is low enough to allow its survival in extreme thermal conditions. It might also function as a means of raising the body temperature up to a level that enables the hornet to remain active even when the ambient temperature is as low as 10 degrees C.

Coherent IR fiber optic bundles for use in IR imaging from 2 to 12 m are fabricated from rigid hollow-glass waveguide arrays. The bore of each hollow glass tube in the bundle is coated with thin films of metallic Ag followed by AgI for enhanced reflectivity. The coating of the rigid bundle is done using liquid phase chemistry techniques applied to all tubes simultaneously. The hollow-glass arrays are composed of up to 900 individual tubes with bore sizes as small as 50 m. Several rigid hollow-core arrays are used to transmit an IR image of a small loop of hot wire and a sample of tissue heated by a CO 2 laser.

Analytical predictions and experimental measurements were highly correlated. The software-controlled system may serve a powerful tool to control thermal side effects during MIS within body cavities.

Abstract-Our investigation entailed a thermal analysis of hornets engaging in ventilation activity at the nest entrance. In the hot summer months, between July-October, ventilating worker hornets are seen just outside the nest entrance, where they assume a typical stance, namely, with their feet erect and fastened to the substrate, their abdomen bent downward at a 90 • angle to the thorax, their antennae vibrating, and their wings beating rapidly for minutes at a time. Eventually these hornets leave their position, either to retreat into the nest or else to fly off to the field, and are replaced by new hornets that assume the ventilation task. Infra-red (IR) photography reveals that in the course of the ventilation activity, the warmest region in the ventilating hornet body is the anterior upper part of the thorax, and the coolest regions are the wings, limbs, antennae and abdomen. This study involved precise and repeated measurements via IR photography of the temperature in the various body parts of the ventilating hornets, and it also offers a preliminary, tentative explanation for the observed differential body temperature. The communication value of the color of the hornet body when ventilating is discussed.

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