Just caught it. Hard as heck to catch. Thier were 6 spots only got 1. Snapped these pics real quick before he backed into the sand. He finally after approx 3 hours made his pit of doom. 2 ants are in there awaiting thier fate. Pics where taken reverse lens.
not sure on max size. they are a larva of another fly, get pretty big then become fly. but i have a few months of enjoyment. hard to catch, so hard to see. get a shovel right beside them and take a bunch out at once. carefully sort through it.
I always thought I was just watching wind blow sand and play tricks with my eyes. I always wanted to know what made those funnel-shaped things.
I learned something new today.