I picked up a nozzle that looked somewhere between a pressure washer and a flamethrower. A little gingerly, I pointed it at a lower corner of the wall, squinted, and pulled the trigger. A soft droning sound started buzzing within the cleaning cart and worked its way up the hose toward the nozzle. I was startled when mechanical mosquitos flew out of the nozzle. They headed straight for the wall and started drilling like they were after blood.

A photo of a mechanical mosquito robot drilling its proboscis into a wall, framed like a Spike Lee film