Duel in Black

In Luna's shroud-like shadows two men lay waiting for each other's move, even their guns obscured. But the dancing space moths weren't fooled.
Young Ron Crag fused the edge of his claim tag to the metal vein in the quartzite rock with his heat gun, then with heavy-shod fingers he tugged at the small copper disk, but it remained firmly in place.
That makes you owner according to law, Mr. Crag, he murmured. In the lonely, rugged reaches of Luna's north country a man had to talk to someone. A real lode looks like. Richest uranium lode I've seen in many a Lunar June. Bring me a nice roll if some of those rotten claim jumpers don't—
Automatically he grasped the hilt of his gun, loosening it in the holster. He sauntered toward the catatread, parked near the southern rim of the small crater, near the mouth of the gorge.
He could see several purple, nebulous space moths fluttering around the engine of his vehicle. Crag watched them as he approached the machine; they dipped, fluttered and weaved about the catatread, many of them wrapping themselves about the warm metal of the engine and eagerly absorbing any heat present. They reminded Ron Crag more of translucent amoeba wreathing through the nothingness of space than moths, but some ancient had dubbed them moths and moths they had remained.
They ranged in size from the area of a man's hand to about three square feet. He knew two things about them; they could detect the slightest rise in temperature over a distance of fifty yards, and they did not like the intense, constant heat of the two-weeks lunar days. They apparently disappeared into craters and fissures during the hotter part of the day, and came out after the setting of the sun.
Good thing my suit and thermocubes are completely insulated, he muttered, or there'd probably be about ten thousand of them wrapped around me, drinking up the heat.
He dropped his hands to the two metal blocks built on to the suit high on each hip. Those two mechanisms were almost as important as his oxygen tank. They generated the heat conducted to the material of the suit and protected him from the 153° C of the lunar nights. Of course, he could last awhile with only one of the units functioning. A man got into the habit of checking them during the long nights; his life depended on them—them and the oxygen tank, and sometimes the gun.