Just noticed this “hatch”? Of miniscule black caterpillar like insect, presume its a larvae stage of something? They seem to congregate at the base of a stone or concrete wall to floor intersection, by the MILLIONS enough to make patches look like thick black velvet! Very delicate, two antennae, 2mm long .5mm wide easily exterminated with ant spray. Should I exterminate to prevent some larger problems in adult stage? What the heck are they, Two photos attached, 1) dispersed on concrete driveway 2) massed together at stone facing.