Hornet silk: Thermophysical properties

Thermoelectric measurements performed on strips of hornet silk have shown marked rise in the electric charge upon increase of temperature between 20°C and 33°C. The increase was dependent on the relative humidity (RH), occurring only at RH above 90%. In tests of heat capacity, hornet silk was found to possessa specific heat of over 2 J/g K within a temperature range of 5-40°C. Observation carried out via transmission electron microscopy (TEM) on silk sections reveal that the silk bears lengthwise electron-dense (dark) stripes separated by light-colored stripes. We assume that in the warm daytime hours, hornet silk can longitudinally transport water that serves to raise the RH and to provide the vaporization needed for nest thermoregulation, whereas at night the very same silk provides an electric charge and longitudinally transfers current and heat.