By Anupum Pant
Wasps are active during the day time, and hornets too. It is during the morning (and the day time, when the sun is out) when they carry out most of their activities like digging into the ground. In fact, there’s a reason why they do it all mostly during the time when the sun is out.
The brown and yellow coloured stripes they have on their bodies are good to warn predators. Besides that they also serve one other interesting purpose – to harvest solar energy!
Researchers have figured that the brown and yellow stripes on the bodies of hornets and wasps have special kinds of gratings that help them to absorb most light, without reflecting much of it. With these gratings they are able to funnel in light from the sun by increasing the surface area for more efficient absorption.
It is believed that when the sun is out, the yellow and brown bands wasps and hornets have on their bodies are able to absorb sunlight and are then able to convert it into electrical energy – which they, purportedly, use to conserve energy and carry out metabolic functions. Researchers also believe that they use up this energy to dig up nests and fight other insects.
Here’s what the paper says:
The complex structure of the cuticle is produced by extracellular secretion from the epidermis. It is constructed as a composite consisting of chitin filaments, structural proteins, lipids, catecholamine derivatives, and minerals. The Oriental hornet cuticle (the exoskeleton) exhibits a brown-yellow pattern…The yellow segments protect the cuticle from potentially harmful solar UV radiation, similar to the role of melanin in the brown color segments of the hornet’s body…The yellow segments contain xanthopterin, which is housed in an array of barrel-shaped granules…the voltage between the hypocuticle and the exocuticle of the yellow stripe showed a negative potential at the hypocuticle with respect to the positive exocuticle. In response to illumination of the yellow stripe, the difference in potentials between light and darkness increases…The fact that the Oriental hornet correlates its digging activity with insolation, coupled with the ability of its cuticular pigments to absorb part of the solar radiation, may suggest that some form of solar energy harvesting is performed in the cuticle.
– (Plotkin et al. 2010:1075)