Beetles’ Food Is Also Their Body Cooler Device

Beetles likely use moist dung balls to keep their bodies cool, reveals a new study.

Dung beetles are known to roll up their balls of excrement to feed their young. They push the ball, weighing 50 times more than their own bodies, across the hot sand to avoid rival beetles competing for the dung ball.

Earlier studies have shown that beetles climb on moist balls to perform a kind of "orientation dance" to work out their way. As experts were expecting to see the beetles' "orientation dance," they noticed that the beetles were climbing on their moist balls often in the midday heat.

Researchers used thermal vision cameras to study the Scarabaeus (Kheper) lamarcki dung beetles in the South African savanna (their native habitat), where the temperature goes beyond 140 degrees Fahrenheit during noon, reported LiveScience.

Experts prepared two circular sandy fields, one was exposed to sunlight and the other was kept in a shady place. 

When experts observed the beetles' behavior, they found that the small insects climbed over the dung balls when their front legs and head faced overheating problems. The beetles that were moving on hot soil were seen climbing the balls seven times more than those that were on cooler grounds.

To find out if the beetles were indeed climbing the balls due to excessive heat, they applied some cool silicone boots to the insects' front legs. These boots gave protection to the legs from overheat. To their surprise, experts noticed that the beetles with boots climbed less number of times on the dung balls.

"Dung beetles are the first example of an insect using a mobile, thermal refuge to move across hot soil," researcher Jochen Smolka, a neuroethologist at Lund University in Sweden, told LiveScience.

"Insects, once thought to be at the mercy of environmental temperatures, use sophisticated behavioral strategies to regulate their body temperature[s]," he said.

Scientists also observed one more unknown preening behavior of the beetles. Once they climbed on the balls, the beetles were most often seen "wiping their faces." They believe that the insects indulge in such a behavior to spread the regurgitated liquid onto their head and legs to cool them.

This unusual behavior in beetles was not seen during other times of the day. Experts are further planning to study the beetles' preening behavior.

The findings of the study, "Dung beetles use their dung ball as a mobile thermal refuge," are published in the journal Current Biology.

To look at how dung beetles roll its balls on hot ground, click here.