Modded playthrough. Can be biter, can be worm. Maybe 1/1000 kills? Could be from a turret kill or a personal lazer kill.

0.001 2017-07-03 20:48:15; Factorio 0.15.26 (build 30561, win64, steam)
0.001 Operating system: Windows 10 (version 1607)
0.001 Program arguments: "C:\Games\Steam\steamapps ...