Dragonflies & Thermoregulation | On foot in the African Bush Part VI

Russet Dropwing, Trithemis pluvialis

The weather has been changing by the day here in the bush, going up as high as 40°C before dropping down to 15°C with strong winds and rain as the wet season finally seems to be blessing us with some much needed water. These variations in temperature are the ideal opportunity to study how Odonates (predatory flying insects like dragonflies and damselflies) regulate their body temperature to fly and hunt effectively!

Dragonflies are primarily ectothermic and therefore rely on external heat sources to regulate their body temperature:

1. Wing-whirring: when they get too cold to fly, dragonflies “shiver”, vibrating their wings to warm up their muscles.

2. Diverting heat: when they get too hot, they can divert heat through the hemolymph (insect blood) that fills the veins in their wings.

3. Sun bathing: like many cold-blooded animals, dragonflies will position themselves in a sunny spot to warm up.

4. Postures: they may also adopt specific postures, like raising their wings to expose their thorax or flattening their bodies against a sunny surface, to warm up faster. Conversely, if they are too hot, they can raise their abdomen vertically to minimize their exposure to sun rays: this is called obelisking.

5. Gliding: dragonflies also control metabolic heat by alternating between powered flight and gliding

We’re looking forward to seeing more of them this summer!