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Thermoregulation

bio_behavior_thermoregulation
"obelisking" Meadowhawk

Thermoregulation is a technical word meaning "control of internal body temperature".  It is a major component of dragonfly behavior. 

Dragonflies need to warm up their flight muscles before being able to take flight.  Heat can either be absorbed by basking in the sun or it can be generated by shivering - a rapid beating of the wings commonly referred to as " wing whirring".

At other times, when the dragonfly needs to cool off, it can be observed pointing its abdomen directly at the sun with its wings rotated downward and tipped slightly forward to shade the thorax.  This is called obelisking.  This position minimizes the surface area exposed to the sun. 

Some species lower their body temperature by making long runs or patrols, diverting hot blood from their core area (thorax) into the abdomen where it is cooled before being returned.  Others simply perch in the shade during the heat of the afternoon.

Varying color patterns can also aid in thermoregulation.  In cool weather darker colors move to the surface of the insect allowing more heat absorption from the sun.  In warmer weather light color patterns help cool the insect.  This change is the result of pigment movements in the hypodermal cells of the exoskeleton.  This is especially common in dragonflies with blue or red markings such as in the darner family.  On a cool morning a blue Darner is more nearly dull gray or pale lavender.  As the insect warms up its original blue color is restored.

A more detailed explanation is beyond the scope of this website.  All you need to remember is that both dragonflies and damselflies are genetically programmed to regulate their body temperatures.  Some species, such as darners and meadowhawks, tend to be a bit more developed than others and can be seen flying early or late in the season in cooler temperatures.

© 2018 Sheryl Chacon Search